Agricultural zoology

The Vertebrate body possesses a bilateral or twosided symmetry; i.e. it can be separated into two exactly corresponding halves, by a plane of division. The bilateral symmetry is strictly carried out as regards the external parts of the body, a single exception to this being flat-fish (plaice, flounder, etc.); but, on the other hand, it is more or less obliterated in the arrangement of the internal organs. In the Vertebrate body we find, as an axis, a vertebral column (backbone) made up of vertebræ, and traversed by the vertebral canal. As soon as this canal widens out in the skull to the cranial cavity, the spinal cord, which it contains, merges into the brain. In addition to the cavity containing the central nervous system, and placed on the upper side (= dorsal side) of the animal, a cavity, the body-cavity, is found in the under side (= ventral side). It contains for the most part the organs of respiration, circulation, digestion, and excretion (Fig. 1), and in Mammals is divided by the diaphragm into thoracic and abdominal cavities. In all the other subdivisions of the animal kingdom the central nervous system is situated in the same cavity as the above-mentioned organs.

Various bones are connected with the vertebral column, and they serve for the attachment of muscles. The bones collectively constitute the skeleton, which is one of the most distinctive features of a Vertebrate.

The animals of this sub-kingdom never have more than four limbs, and their blood is red, while that of most other animal groups is colourless.

The structure of the heart in the various Vertebrates must also be noticed. In no Vertebrate is this organ so simple in structure as in the scheme given in Fig. 6; such an arrangement, moreover, would involve great difficulties. One great difficulty would be that while the blood was leaving the heart at a (Fig. 6), no fresh blood could enter, so that the blood in the veins would stand still. Even in the lowest Vertebrates (the Fishes) this difficulty is obviated, for where the main vein (or veins) opens into the heart an enlargement of this vein is found, where the blood can collect as long as the heart continues to contract. This expansion is also reckoned as part of the heart, and named the auricle (Fig. 8, V.K.), while the heart proper is termed the ventricle (K.). It is also easy to see that there must be a tolerably wide opening between the two chambers, so that as soon as the ventricle becomes flaccid the auricle can force blood into it. But there being such a wide aperture between auricle and ventricle, one valve is not enough to make it impossible for the blood to pass back into the auricle during the contraction of the ventricular walls. There are two or three valves there (Fig. 8, Kl.) fixed by fibres to the wall of the ventricle. In order that the blood which is forced into the artery (S.A.) may not pass into the ventricle during its relaxation, there is another valve (not indicated in Fig. 8), at the base of the artery.

An arrangement like that so far described is found in fishes. The heart consists in them of an auricle, into which is returned the blood that has traversed the body, and of a ventricle which moves it on again. But the blood that has traversed the body is on that account poor in oxygen, and consequently unfit to be circulated again when it is returned to the heart. It is necessary for it to take up fresh oxygen before being circulated again. In fishes this difficulty is met by the blood, poor in oxygen, which flows out of the ventricle, first going to the gills and streaming through them. The gills consist of a very large number of small, thin-walled outgrowths arranged in regular rows on the firm gill-arches. The blood, poor in oxygen, passing out of the ventricle and through various arterial branches to the gill-filaments, takes up fresh oxygen as it streams through these from the oxygen dissolved in the water which constantly surrounds them. For this purpose a stream of pure water is regularly taken in by the mouth and expelled again, right and left, through the gill-slits. The blood, having become rich in oxygen in the gills, is now once more fit for circulation through the body, and therefore flows out of the gill-capillaries into larger vessels, which finally unite into a single large vessel that carries the purified blood to the various parts of the body. In the arrangement of the heart here described there is the disadvantageous condition that the blood is obliged to traverse two sets of capillaries (gill and body capillaries). This is not an easy matter, for there is a great deal of friction between the blood and the walls of the capillaries, constituting a hindrance to its progress. The circulation of the blood in fishes is consequently very slow, and since the blood contains the oxygen which is used by the various parts of the body, oxidation goes on slowly in the body of a fish; hence the small amount of heat developed there. Since fishes almost immediately give off to their surroundings the small amount of heat which they develop, they have no constant body temperature, varying in this respect with the temperature of the surrounding water. Such animals are termed cold-blooded.

In all other Vertebrates a more rapid movement of the blood is rendered possible by the insertion of a second heart, quite similar in every respect to the other heart, in the course of the blood between the respiratory organs and the body. The first heart drives the blood through the lung capillaries, and therefore corresponds to the fish-heart; from these capillaries the blood returns to the auricle of the second heart, and from the ventricle of that heart travels to the various parts of the body. When it has completed this course, it returns to the auricle of the first heart. Although these two structures work independently, they lie close together and make up a single organ. We do not therefore speak of two individual hearts, but of one heart with two halves. The first half, which receives the blood, poor in oxygen, that is returned from the body, and sends it on to the lungs, lies on the right, and is termed the right half. The second half, which receives the richly oxygenated blood from the lungs, and pumps it to the various parts of the body, is termed the left half (Fig. 9 and explanation).

In the arrangement just described, which is found in Mammals and Birds, the blood returning from the lungs is propelled with new force through the body, and therefore circulates very quickly, so that the various parts receive a relatively large amount of oxygen in a short time. It is therefore intelligible that Birds and Mammals develop more warmth than Fish. They possess a special, constant body temperature, somewhat different in different species, but usually lying between 98° and 104° Fhr., and they are called warm-blooded animals.

In Reptiles (snakes, lizards, etc.), the two halves of the heart are not entirely distinct, since there is an opening in the partition-wall between the two ventricles. As a consequence of this, the poorly oxygenated blood of the right half of the heart mixes with the richly oxygenated blood of the left half, the extent to which this mixing takes place being proportional to the size of the aperture. In Reptiles, therefore, the blood supplied to the lungs is not so poor in oxygen as it might be, nor, on the other hand, is the blood supplied to the other parts of the body completely oxygenated. As consequences of this: (1) respiration is feebler, and (2) the development of heat less than in Mammals and Birds (i.e. reptiles are cold-blooded), and (3) the chemical changes taking place in the body (the metabolism) go on more slowly than in warm-blooded animals, and we can understand why reptiles execute fewer movements in a given space of time.

In Amphibians (e.g. frog) the two ventricles are similarly connected, but the opening is still larger than in Reptiles, and the partition-wall may even be altogether absent. It follows, therefore, that the mixing of the two kinds of blood is still more complete, and that Amphibians, too, are cold-blooded.

The vertebrate sub-kingdom embraces the classes of I. Mammals; II. Birds; III. Reptiles; IV. Amphibians; V. Fishes.

CLASS I.: MAMMALIA (SUCKLERS).

Warm-blooded Vertebrates (p. 16), usually covered with hair, and bringing forth living young, that suck for some time after birth. The female is provided with milk-glands on the thorax or abdomen, or both those regions.

Speaking quite broadly, the skeleton is like that of man, described on pp. 4–8. There are, however, great differences in detail. The cranium is relatively much smaller, and the bones of the face (especially of the jaws) are usually much larger than in the human skull. The number of the cervical vertebræ is seven in all Mammals, as in man; but the other kinds of vertebræ vary in number in the different species. The number of caudal vertebræ, for example, is very variable. As most Mammals go on all fours, their fore and hind limbs are much more similar than is the case in man. In many the thigh and upper-arm bones are drawn closely up to the body (horse, ox, pig). Mammals never have more than five fingers or toes, but may have fewer. The thumb or great toe is the first to disappear (hind foot of dog, fore and hind foot of pig). There may be only three (rhinoceros), two (ox, sheep), or one (horse) digit developed. In addition to fully developed digits, there are in many Mammals very small stunted ones (“dew-claws” of the stag).

There are also great differences in the way of resting the feet on the ground. Man and bear tread on the soles of the feet (plantigrade); dog and cat walk on the under side of the toes (digitigrade), not on the other parts of the feet. Ox, pig, horse, etc., rest while walking only on the tips of the toes, which are sheathed in hoofs (unguligrade).

The teeth of mammals are wedged into special sockets in the jaw-bones. The structure of a mammalian tooth is made clear by Fig. 12. We first distinguish a pulp-cavity (p), which in the living animal is filled with a substance supplied by a bloodvessel and nerve. This cavity is surrounded by the dentine (d), a hard substance which makes up the greater part of the tooth. Hard enamel (s) covers the whole of the crown in man and many animals, while in certain other forms it is found only on part of the crown. The root of the tooth is covered with cement (z), a bone-like substance.

All teeth in which the entire surface of the crown is covered by enamel only are known as simple teeth, while those into which the enamel only penetrates in more or less deep folds, leaving the rest of the crown uncovered, are known as compound teeth (Fig. 13). The structure of the teeth is related to the nature of the food. We distinguish three kinds of teeth in the same animal, which, however, are not all present in every species; these are the incisors, canines, and grinders. The first two kinds are changed; but only the anterior grinders, known as the premolars, are changed, while the hinder ones, the true molars, do not first appear as “milk” teeth, but rather later on with the other “permanent” teeth.

The following orders of Mammals are distinguished: I. Bimana (Man), II. Quadrumana (Apes), III. Carnivora (Beasts of prey), IV. Insectivora (Insect-eaters), V. Cheiroptera (Bats), VI. Rodentia (Gnawers), VII. Ruminantia, VIII. Solidungula, IX. Pachydermata, X. Cetacea, XI. Edentata, XII. Marsupialia (Pouched animals), XIII. Monotremata.

I shall deal here only with those orders which are of agricultural importance.

In each jaw there are six relatively small incisor teeth; and, on each side of these, a large projecting canine, by which the flesh is torn from the body of the prey (Fig. 14). The premolars and the first of the true molars (the carnassials^[2]) are strongly compressed, and have a cutting crown; their outer surface is completely covered with hard enamel. As the lower jaw is smaller than the upper jaw, and is only able to move up and down, not from side to side, the sharp crowns of the premolars, and especially those of the large carnassials, cut along one another, and divide anything coming between them as if with shears. The small molars which are usually found behind the carnassials have broad tuberculated crowns. The temporal (i.e. chewing) muscles are strongly developed, the general result of which is that the head is broad. The claws are very sharp in some of the families. The Carnivora are powerful animals, move very quickly, and are endowed with keen smell and sight.

The wild Carnivora living in Britain belong to the families of cats, dogs, and weasels.

Family: Felidæ (Cat Family).

Typical Carnivora with very large canines and carnassials, two premolars in each half of each jaw, one of the upper molars, but none of the lower ones, small and tuberculated. Tongue rough. Fore and hind feet five-toed. When not in use, the claws are drawn back (retracted). The Felidæ are digitigrade. Backbone very flexible, and with free power of movement. The Felidæ are bloodthirsty, nocturnal animals, many of which climb well, and spring upon their prey.

The group is specially exemplified by the Domestic Cat, the parent stock of which is the Nubian cat (Felis maniculata), a native of Nubia and the Soudan. The Wild Cat (Felis catus) is larger than the common kind, and has a thicker tail. Formerly it was tolerably common in Britain, but now only occurs in a few thinly populated districts.

The Lynx (Felis Lynx), found at one time in Germany, still lives in the Carpathians, and in Switzerland, but occurs more commonly in Scandinavia, Denmark, and Russia.

Family: Canidæ (Dog Family).

Head longer than in cats; canines and carnassials relatively less developed. Two tuberculated molars on each side of each jaw. Claws not so sharp as those of cats, and cannot be drawn back (i.e. are nonretractile). Fore-foot five, hind-foot four toes. Tongue smooth.

The various races of the Domestic Dog belong here.

The wolf (Canis lupus) is no longer an inhabitant of Britain or Germany, but sometimes crosses the German frontier from Russia, Galicia, Hungary, the Alps, and the Ardennes, especially in winter, and preys upon the larger domestic animals.

The remaining example is—

This animal lives in an underground dwelling, which is either dug out by itself or else is a deserted badger-burrow. It kills roes, fawns, hares, and game-birds; in farms it preys on poultry and eggs. It never commits depredations in the neighbourhood of its burrow, for fear of betraying its hiding-place. Valuable services, however, must be balanced against the damage mentioned above, for it catches many rabbits, and also an enormous number of field-voles in the years when these become a pest. It also often eats insects (e.g. cockchafers), worms, and snails. In fact, the fox is perhaps generally of more use than otherwise to the farmer and forester.

Family: Mustelidæ (Weasel Family).

Elongated, slender; legs short; head small and flat; cranium elongated; tongue smooth. Five toes on each foot, with small, sharp claws. A tuberculated molar on each side in the upper and lower jaws. The weasels give out an offensive odour from stink-glands situated near the anus.

There belong to this family—

1. The Pine Marten (Mustela martes). Body up to twenty inches, tail up to ten inches long; fur brown, with yellowish wool-hairs; a yellow patch on the throat. Is found in thick woods, where it destroys small birds and squirrels; it also kills much poultry and game.

2. The Beech, or Stone Marten (Mustela foina). About as large as the preceding species; greyish-brown fur, with whitish wool-hairs; a white patch in the throat; chiefly occurs in the immediate neighbourhood of human dwellings, in barns, wood-stacks, etc.; kills a great deal of poultry, sometimes also wild birds, mice, and game.

3. The Polecat (Putorius fœtidus). Shining brownish black, with yellow wool-hairs; somewhat smaller than the stone marten; in particular, the tail is shorter and its hair is not so long as in the two preceding species. In the summer it lives in the open country, in hollow trees, or in the burrows of foxes and rabbits; in winter it settles down near human dwellings, where it lives in wood and under heaps of brushwood, haylofts, etc. In summer it may do more good by destroying numerous field-voles, water-rats, etc., than harm by devouring those singing birds which are favourable to agriculture; but in winter its undesirable visits to the fowl-house and dove-cot effect much injury. It kills the birds and devours the eggs, sucking without smashing them. In winter, too, it is very harmful to beehives, being fond of honey.

The Ferret (Putorius furo) is undoubtedly a short-legged variety of the common polecat, usually white in colour, and, when that is the case, red-eyed.

4. The Stoat, or Ermine (Putorius erminea). Body twelve inches, tail about three and a half inches long; slender; the body is scarcely broader than the head; tail longer than in the next species; summer fur, cinnamon brown above, white below; tail, cinnamon brown with black tip; winter fur quite white, but the end of the tail remains black. Mostly in fields, in the neighbourhood of plantations or woods; always abundant among sandhills, owing to the rabbits living there. The stoat usually follows its prey at night, stealing upon mice, rats, rabbits, hares, and song-birds; it is also sometimes very destructive in dove-cots and hen-houses. It must, however, be stated that the stoat is on the whole more useful than harmful.

5. The Weasel (Putorius vulgaris). Smaller than the stoat; head larger and thicker than the extremely slender, almost snake-like, trunk; legs short. The weasel is a very sharp little animal, and can easily pass along mouse-holes. Summer and winter coats alike—back brown, belly white. Its food chiefly consists of field-voles, also of rats and water-rats, young hares and rabbits, birds building near the ground, and also their eggs, which the weasel, by holding under its chin, manages to carry to its home; occasionally also lizards, blindworms, snakes, and frogs. The weasel does some damage in fowl-houses and dove-cots, and is also destructive to game. This, however, does not outweigh its very great use, since it is above all an untiring vole-catcher. When in any region the field-voles have multiplied excessively, an immigration of weasels takes place from surrounding parts. In years when there is a plague of voles the usual breeding time in spring is followed by another later on. A very large number of weasels may be found in a vole-infected district, and they thin out the mischievous rodents in a surprising manner. Nor are the weasels less useful in summer than in winter. They even follow under the snow the voles which winter in the country, and the slaughter effected at this period must exert a great influence on the following season, when these animals recommence their injurious work, and a pair of them that have survived the winter may perhaps produce two hundred others before the end of the summer.

6. The Mink (Putorius lutreola) is as large as a polecat, and may be regarded as a sort of link between it and the others. Leg and ears short; skin smooth-haired, brown both on the back and the belly; chin, lips, and a small patch on the neck, white; tail about one-third the length of the body. In well-watered regions on the banks of rivers, lakes, and ponds. Eats water-rats, water-birds, frogs, salamanders, fish, crayfish, water-insects, water-snails, and aquatic bivalves. Holstein, Mecklenburg, Pomerania, Brandenburg, Silesia.

7. The Otter (Lutra vulgaris). Body flattened; legs short, with webbed toes; snout rounded; ears short, and can be closed by a fold of skin; tail flat, and pointed at its tip. Length of the body, twenty-eight to thirty-two inches; of the tail, fourteen to sixteen inches. Skin smooth-haired, shining dark brown above and below. Found on the banks of lakes, pools, ponds, rivers, brooks, etc., where fish is plentiful. It catches water-rats, ducks and geese, as well as their young, wild water-birds, frogs, fish, crayfish, water-insects. Especially destructive to fish.

8. The Badger (Meles taxus). Body heavy; legs short, plantigrade; toes with strong digging claws; snout pointed; canines not very large; both they and the carnassials much worn in old animals. Tuberculated molars well developed. The dentition and whole structure of the body show that the badger is not exclusively a flesh-eater. Length of body, three feet; weight, 22 to 33 lbs. Fur tolerably long-haired, yellowish whitey grey, mixed with black. Head with longitudinal stripes of black and white; tail short, yellowish grey.

The burrow is very large; several passages, the openings of which may be ninety-seven feet apart, lead to the exterior. The badger only leaves its dwelling in the evening. It eats mice, birds which nest on the ground, especially their eggs and young, snakes, frogs, cockchafer grubs, earthworms, insects; also turnips, carrots, acorns, and sweet fruits. Although it is both harmful and useful, the latter is more generally the case. Its digging habits, however, are sometimes destructive, since it throws up young trees and other plants by the roots. The badger often sleeps several days in succession during the winter, although it does not hibernate. Its fat is used up during the winter.

Order: Insectivora (Insect-eating Mammals).

Since the Insectivora feed upon very small animals (insects, worms, snails), they cannot themselves be large. Only those species (hedgehog) which feed on small mammals and birds or upon vegetable matter, in addition to insects, are of medium size. The native species all live on or in the ground. The snout is extremely slender, and does duty as an organ of touch. The eyes are usually very badly developed. Incisors sharp; and the back teeth, which are completely coated with enamel, are remarkable for their pointed crowns. When the mouth is closed the upper teeth fit into the spaces between the lower teeth, and vice versâ. Consequently the shutting of the mouth forces the points of all the back teeth into any insect which happens to be between the jaws. The Insectivora are plantigrade (p. 22). Here belong the following forms: the Shrews (Sorex), the Mole (Talpa europæa) and the Hedgehog (Erinaceus europæus).

The Shrews (Sorex) are small animals with a superficial resemblance to mice, with slender soft-haired bodies, small eyes, and tolerably long, thickly haired tails. Shrews are extremely voracious, eating daily more than their own weight of food, and destroying an enormous quantity of subterranean vermin. They live in underground passages, not usually made by themselves, but dug out by field-voles. They smell strongly of musk, secreted by two glands in the hinder part of the body.

The blackish brown Shrew-mouse, or Common Shrew (Sorex vulgaris), and the Lesser Shrew (Sorex pygmœus), only about two inches long, kill, in the cornfields, gardens, or woodland, an enormous quantity of noxious insects found in the earth, together with their larvæ; also snails and worms, and sometimes field-voles, and are in the highest degree serviceable. But the larger (up to 3½ inches long), black Water Shrew (Sorex fodiens), although serviceable on land in the same way as the other kinds, is very injurious to fishing and fish-breeding, since it devours the small fish and kills the larger ones, eating out their eyes and brains.

The Mole (Talpa europœa). Body thick, cylindrical. Legs short, fore legs broad and spade-like, with broad digging claws. Eyes small, scarcely visible among the fur. No external ears; the auditory opening can be completely closed by a fold of skin. Shining black fur. The mole is found in every soil inhabited by insects and earthworms, provided it is not too stiff, but yet sufficiently coherent to dig passages in, which will not at once collapse. Its presence is known by the heaps which it throws up. The nest, however, is always found under a larger heap, frequently hidden under tree roots, walls, etc., though sometimes in the open field. It consists in the first place of a nearly round dwelling-chamber, softly upholstered with vegetable substances; this is surrounded by a labyrinth of passages. From the nest a passage runs to the mole’s hunting-ground. The walls of this passage of the labyrinth, and of the nest, are hard. The wider and subterranean channels, which the mole digs out when it is simply catching insects in the soil, easily fall in again, and the animal takes no pains to compact their walls. The highway to the hunting-ground, in which the animal can progress very rapidly, can be at once detected, not like the ordinary passages by a small chain of mole-hills composed of the thrown-up earth, but by a depression, since in its preparation the earth is laterally compressed and not thrown out. This tube is shorter or longer according as the hunting-ground is in the immediate neighbourhood or further off; it may be 100 or 160 feet long. The mole sleeps in the nest during the time not employed in seeking for food, and goes three times a day on the hunt for insects (early morning, midday, and before sunset in the evening). Having reached the subterranean hunting-ground, it tracks to some distance the insect larvæ, and worms found in the soil, being aided in this by its long snout. It daily devours more than its own weight. During summer the mole digs its passages near the surface, since larvæ and worms are then found in the uppermost layer of earth. In winter, when these withdraw into the depths of the soil, it digs much deeper channels. It does not fall into a winter-sleep. The young (three to seven) are born in May, June, or July. The mole never gnaws plants. It does service, sometimes very great, by eating many wireworms, grubs, snail embryos, earth caterpillars, mole-crickets, and other earth-inhabiting insects, as well as their larvæ. It also willingly eats earthworms, but whether this does good is not definitely known. But under certain conditions it may also do harm, rooting up plants as it makes its heaps. Grass and grain suffer little, if at all, by this; other plants more; while young flax-plants perish if their roots are loosened. Mole-hills in hayfields and cornfields are a nuisance at harvest time. Moles are not to be endured in the neighbourhood of dams, since their borings may become the immediate cause of flooding. Trapping may usefully be resorted to in cases where moles are harmful.

The Hedgehog, or Hedgepig (Erinaceus europæus). When danger threatens it rolls itself into a ball covered all over with prickles, and is in this way secured from the attacks of most enemies. The hedgehog goes on the hunt in the evening; while during the day it sleeps in its hiding-place, situated in such places as the side of a ditch, hedges, or under heaps of brushwood. It preys more particularly on field-voles, sometimes also on eggs and small birds (chickens occasionally), lizards, grass-snakes, adders (by the bites of which it is unaffected), frogs, cockchafers and their larvæ, field snails, earthworms, and similar small deer; now and then on fallen fruit and juicy plant roots.

Order: Cheiroptera (Bats).

All Bats, except a few tropical genera, feed on insects, and possess teeth like those of the preceding order of Mammals (p. 30). The leading feature is the characteristic modification of the fore limbs into a flying apparatus. The bones of the fore arm (Fig. 18, u, r), the metacarpels (mc), and the phalanges (except in the case of the thumb, which possesses a sharp claw (p)) are of great length; and between the long fingers, between the fore and hind limbs, and, last of all, between the two hind limbs there is an elastic membrane, serving both for flight and touch. Sight ill developed, since the bat is a nocturnal animal; a delicate sense of touch has its seat not only in the flying-membrane, but also in the skin of the ears, which are often very large, and in the membranous flaps which, in a few genera (the “leaf-nosed” bats), occur on the nose and lips. As is well known, bats sleep in the day; and they also hibernate in chimneys, hollow trees, ruins, and other similar places of concealment.

They principally devour night-flying moths, and spiders; and, since they use a great quantity of nourishment, are of great service, since the caterpillars of many of the species they destroy are very injurious to agriculture or forestry. About nine species live in Britain, but there is no use in enumerating them here.

Order: Rodentia (Gnawing Mammals).

Two long incisors (Fig. 19), the crowns of which are continually being worn down, while a corresponding growth takes place at the root-end. These incisors are used for gnawing, in which process the lower jaw is rapidly moved backwards and forwards. Gnawing wears down these teeth less in front than behind, owing to the presence of a thick layer of enamel in the former position. Their crowns, therefore, maintain a chisel-edge. That the incisors never stop growing is clearly seen when the usual wearing down does not take place, as, e.g., when the lower jaw is placed obliquely under the upper jaw, or when a tooth is absent in one jaw, under which circumstances the corresponding incisor in the other jaw is not worn down. In such a case the incisors continue to grow, ultimately curving upwards or downwards, and becoming tusk-like structures (Fig. 20). The Rodents have no canines. In those Rodents which feed both on animal and vegetable food (the “Omnivora,” e.g. squirrel, common mouse, brown rat, etc.), the crowns of the back teeth are completely covered with enamel; in the purely vegetable feeders (“Herbivora,” e.g. hare, rabbit), they are compound teeth (p. 22). In most Rodents the hind feet are longer than the fore, giving a springing gait. Eyes large. Many forms have “cheek-pouches,” in which the food they obtain can be stored up for some time. When the pouches are full, a muscle contracts by which their ends are drawn backwards; they are emptied by the animal pressing them with its fore feet. The majority of Rodents are small, they are at most of medium size (hare). The majority of the species have great powers of reproduction, by which the injurious kinds are sometimes rendered a very great pest. The British forms injurious to agriculture principally belong to the families of hares, mice, and voles. The squirrel (Sciurus vulgaris), and the dormice (especially Myoxus avellanarius) are solely of importance in forestry.

Family: Leporidæ (Hares and Rabbits).

Skull somewhat long. Two small incisors behind the two large upper ones. Ears long and spoon-shaped. Upper lip cleft. Back teeth with enamel folds. Here belong the hare (Lepus timidus) and rabbit (Lepus cuniculus).

Hare (Lepus timidus). Ears longer than the head. Eyes yellowish brown. Fur rusty yellow to grey on the upper side, white on the under side. The doe litters in an open “form;” the young are born covered with hair and with open eyes. Mature animals breed four or even five times a year, producing two to four leverets each time. The hare is injurious to agriculture, eating cabbages, rape, turnips, clover, vetches, young corn plants, carrots, and grass. It also eats many weeds. It is, however, less injurious than the rabbit, for it does not burrow. The damage done by the hare is also less evident, since this restless, fastidious animal seldom feeds continuously in the same spot.

Rabbit (Lepus cuniculus). Ears shorter than the head. Eyes dark brown. Fur yellowish brown to greyish yellow on the upper side, redder in front. Under fur bluish grey. Shape more compressed. The rabbit breeds more rapidly than the hare. Five to six times yearly the doe brings forth four to eight young, which, after six months, can again reproduce. Dwelling subterranean. Young, blind and hairless at birth. As the rabbit burrows, it is limited to certain districts, for the soil must not be too stiff and firm, nor, on the other hand, too light and incoherent. The rabbit is injurious in the same way as the hare, but the damage is more obvious (see above); and as a result of its burrowing habits it does infinitely more damage. Both in sandhills and in alluvial sandy soil rabbit burrows lead to the blowing away of material only held together by sand-plants. Kept down by shooting, netting, and ferreting (p. 27).

Family: Muridæ (Mouse Family).

The mouse-like animals (the larger species of the family are called “rats”) closely resemble the representatives of the following family, but are distinguished from these (the “voles”) by their slender body, longer legs, a more pointed head with longer always clearly visible ears, and usually, with the exception of the hamster, by a tail equal in length to the body. The hind legs are longer than the fore legs, hence the hopping mode of progression. Three back teeth on each side of each jaw, possessing a tuberculated crown completely covered with enamel.

The Hamster (Cricetus frumentarius).—The Hamster has cheek-pouches, and a very short, thick, but short-haired tail. It attains the size of the brown rat. Bright yellowish brown; belly and legs black. The hamster is found almost exclusively on fertile soil devoted to cultivation. It appears locally, and then for several years in great abundance, so that it is often caught in tens or even hundreds of thousands. Favourite food: wheat, field beans, and peas, then rye and similar grain; and, last, roots, turnips, young corn plants. Sometimes, too, the hamster eats animal food—worms, insects, lizards, small birds, eggs, and mice. As a winter store it usually only accumulates grain, beans, and peas in its hiding-place, often to the amount of more than five gallons. A little heap of thrown-out soil marks on the surface the position of its nest. The entry to this runs vertically down into the soil. Six to twelve young, twice a year. The dwellings of the hamster, which are situated in stubble-fields, can easily be found; and by digging them up, particularly in spring and late summer, when there are young ones, the number of these destructive Rodents can be greatly reduced. May be caught in traps.

Genus Mus (Mice and Rats) includes Rodents without cheek-pouches, and with long, scaly, ringed tails. Two large species (“rats”) belong here, namely—

The common Black Rat (M. rattus), indigenous to Europe since pre-historic times, and the stronger, somewhat larger—

Brown Rat (M. decumanus), with greyish white belly (while the first-named species is black on the upper and only slightly brighter on the under side). The brown rat migrated during the first half of the eighteenth century from Asia into Russia, and about the same time from Further India to England by means of ships. Since then it has spread all over Europe and other parts of the world, and in many regions has quite driven out the black rat. Both kinds of rat eat almost everything, and are a pest in housekeeping, as well as in agriculture. They feed on insects, mice, eggs, and chickens, will even bite pieces from the living bodies of grown poultry and fattening swine, and also devour young geese and ducks. They eat grain, peas, beans, potatoes, carrots, turnips; bread, cheese, and similar provisions. Multiply very rapidly. Can be driven away by clacking-mills, and to a great extent by noise. Caught in traps.

Besides these, four mice belong here:—

The Common Mouse (Mus musculus). Back yellowish grey-black, gradually shading into a somewhat lighter tint on the under side.

The Wood Mouse, or Long-tailed Field Mouse (M. sylvaticus). Back a brown shade of yellowish grey; belly white, sharply marked off; relatively very long hind legs, hence a hopping gait. The long-tailed field mouse penetrates tolerably far into woods, but is also found in plantations and gardens, sometimes also in quite treeless regions. On arable land it may adopt the habits of the field vole (p. 42), but as it does not multiply so rapidly is not nearly so injurious. It may also live either for a short time or permanently in houses, adopting the same habits as the common mouse.

The Harvest Mouse (M. minutus). Small, pretty; back yellowish brown red, belly of a sharply marked-off white. Lives in cornfields during the summer; in harvest time by the field-paths; during winter in barns and haystacks, but also in outdoor nests in the fields. Climbs among the grass and corn-haulms, and the small stems and branches of other plants, including shrubs, holding fast, not only by the feet, but also by the tail. Builds a beautiful spherical nest with a side entrance out of the haulms and leaves of grass and corn, or out of other leaves. Devours seeds, especially grain, oats being the favourite.

The Corn Mouse (M. agrarius). Back brownish red with longitudinal black stripes. In plains east of the Rhine. Usually local, but then very abundant. Chiefly in cornfields and fruitfields; digs holes in the soil. In autumn it often occurs in the field in large colonies. Food: grain, beans, peas, potatoes, turnips, carrots. In winter in the barns and dwelling-houses of farmers.