Fig. 40.—Male and Female Capercailzie (Tetrao urogallus).
The species here included differ very much among themselves; but all seek their food, which is almost exclusively of animal nature, at the water-edge (rivers, brooks, lakes, ditches, canals, seashore) or in damp places (damp meadows and ploughed fields, moors, swamps). They are, therefore, adapted to wading, and for this purpose have a long featherless tarsus, while the lower half of the long shank is quite bare and covered with horny scales. In flight the wading-birds do not draw their legs up to their body, as is the case with the birds already spoken of, but stretch them out behind to their full length. Monogamous. Young precocious (p. 51), except in storks and herons when they are nestlings. The shore-dwellers eat fish, bivalve molluscs, etc.; only those species living on damp meadows and fields are of use to agriculturists, by devouring insects, snails, and worms. These are indicated by the letter u in the following list of the commonest native kinds:—
Fig. 41.—The Pheasant (Phasianus colchicus).
Coot (Fulica atra); Water Hen (Gallinula chloropus); Corn Crake (Crex pratensis, u); Plovers (Charadrius, u); Pewit or Lapwing (Vanellus cristatus, u); the Snipes (Scolopax); the Curlews (Numenius, u); the Stints (Tringa); the Godwit (Limosa ægocephala, u); the Sandpipers (Totanus, u); the Heron (Ardea cinerea).
Fig. 42.—The Woodcock (Scolopax rusticola).
These birds are distinguished by their swimming powers and corresponding organization. Legs usually set on far back, shorter than the body. The feet in particular are adapted for swimming. In some swimming-birds each of the forwardly directed toes has a webbed margin (“split swimming feet,” Fig. 43); in others, the three front toes are all united by a web (Fig. 44), while the hind toe is either small or wanting (“swimming feet”); lastly, there are some in which all the toes are forwardly directed and united by a common web (“oar-feet”). The plumage of swimming-birds is compact, and always kept greasy by the secretion of the oil-gland. I shall speak of two families only.
Fig. 43.—Crested and Little Grebes (Podiceps cristatus and minor).
The inner margin of the beak is covered by skin, thrown into transverse ridges or tooth-like projections. Swimming feet (Fig. 44). Tolerably long wings; remarkable powers of flight. Feathers soft. These birds mostly affect shallow fresh water, in which they get their food by grubbing in the mud, the soft skin of the beak serving as an organ of touch. Polygamous. Young precocious (p. 51).
Here belong—the long-necked Swans (Cygnus) and the thick short-necked Geese (Anser), in which the beak is higher than broad at its base; the Swimming Ducks (Anas) with broader beaks, the Diving Ducks (Fuligula), and Goosanders (Mergus) with a broad hanging web to the hind toe. None of these birds are useful, while wild geese and ducks are harmful.
Fig. 44.—Goose (Anser cinereus).
Three species of wild Geese (Grey Goose = Anser cinereus, Bean Goose = A. segetum, White-fronted Goose = A. albifrons) chiefly breed in Eastern or Northern Europe, and only come to Britain in autumn or winter, flying about in flocks. They eat the grass in low-lying meadows, and even pull it up by the roots; in the cultivated fields they devour winter corn and winter rape, and tread down more with their clumsy feet than they eat. They are also harmful to vegetable growth, owing to the very caustic nature of their dung, which is often deposited in large quantities in one place. In regions where they breed they also devour both ripe and unripe grain. Where they only occur in autumn, they scrape potatoes, turnips, and carrots out of the ground in order to eat them. Flocks of geese fly in a slanting line or in the form of a ploughshare.
Among Swimming Ducks damage is only done by the Wild Duck (Anas boschas). It breeds wherever there are fresh waters. Nests amongst grasses or swamp-plants, or in a tree. The wild ducks remain the whole winter as long as the waters are not frozen, otherwise they go off for a short time to the south. Food: the tops of stems, buds, leaves of various water-plants, also barley, oats, and other grain; water-insects, fish, and fish-spawn. These ducks also do damage in cornfields by treading down and cracking the plants.
Usually swimming feet. Legs tolerably long, adapted for wading (Fig. 45). Wings long, pointed. Beak laterally compressed. Young nestlings (p. 51). Breed in larger or smaller flocks, usually on the coast, occasionally on the margin of fresh waters. They chiefly feed on fish, worms, molluscs, and crustacea; sometimes, in the case of a few species, on young birds and eggs, as well as mice and other small mammals. Gulls are usually of no importance in agriculture; but the Black-headed Gull (Larus ridibundus), which breeds on the banks of lakes and rivers, devours many cockchafers and other noxious insects. The Herring Gull (Fig. 45), Kittiwake (Larus argentatus and L. tridactylus), and a few other species, which breed on the coast, sometimes show themselves inland, especially in stormy weather; they then pursue field-voles, and catch many injurious insects.
Besides the true Gulls (Larus), I will only mention the Sea Swallows (Sterna), with forked tails.
Fig. 45.—Herring Gull (Larus argentatus).
Cold-blooded Vertebrates (p. 19). The heart has the same structure as in Mammals and Birds, but the left and right ventricles are usually only incompletely divided from one another (p. 20). The body is invested with horny scales or with bony plates covered by a horny layer. Reptiles are very unlike Birds in appearance, but present many essential points of resemblance to them in their skeleton; indeed, during earlier geological times, there were transitional forms between the two classes. The structure of the reptile egg, too, is very similar to that of the bird’s egg; but the first has no lime-salts deposited in its shell. The egg is not hatched out by the animal itself, but exposed to the heat of the sun or to the warmth developed by decaying vegetable matter. Several reptiles (adder, for example) keep their eggs in their bodies till the young escape. Reptiles have either no limbs (snakes, a few lizards), or, at any rate, the limbs are not well developed, and are so placed that the body does not rest upon them, but is slung between them.
Fig. 46.—Common Lizard (Lacerta agilis); 2, head of the same from below; 3, tongue.
The Reptilia are divided into the Orders of Crocodilia (Crocodiles), Chelonia (Turtles and Tortoises), Lacertilia (Lizards), Ophidia (Snakes).
Fig. 47.—The Adder (Pelias berus).
Our native reptiles have no agricultural importance. I will, however, briefly mention the Adder (Pelias berus, Fig. 47), as it is dangerous to man. Head broad; tail much smaller than the hinder end of the body. Colour greenish grey or brownish. A black zigzag band runs along the dorsal side of the body. Length about twenty inches. The two hook-shaped poison-fangs are found in the front of the upper jaw; opening the mouth widely causes them to be erected. They are traversed by poison-canals through which the poison flows immediately into the two bloodless wounds. The adder lives in woods and on mountain slopes, where it devours mice. The poison has a decomposing action on the blood; it causes fever, and swelling of the part bitten, as well as sometimes of the neighbouring parts. The bite may be fatal. Alcohol is spoken of very highly as a remedy.
Fig. 48.—The Grass Snake (Tropidonotus natrix).
Fig. 49.—Blindworm (Anguis fragilis).
The native Ringed Snake (Tropidonotus natrix, Fig. 48), three feet long, is bluish with belly flecked with black and white; a yellow and a black band on the neck. It is fond of going into the water, and eats frogs, newts, and insects. The Smooth Snake (Coronella lævis), two feet long, is brown, with black patches on the back, which, however, do not form a continuous band. Head dark velvety black. Devours lizards and blindworms. The Blindworm (Anguis fragilis) is indeed snake-like, or rather worm-like (Fig. 49), but nevertheless belongs to the lizards, with which its internal structure agrees.
Fig. 50.—Great Crested Newt (Triton cristatus); male above, female below.
Cold-blooded Vertebrates (p. 19). The heart has only one ventricle and two auricles (cp. p. 21). The skin is naked, damp, usually slippery and smooth; it helps in respiration. Although several Amphibians resemble various Reptiles in outward appearance (Newt and Lizard, Figs. 50 and 46), the structure of the skeleton is quite different. Upon the whole, Amphibians resemble fishes more closely, and they breathe by gills when they are young, which strengthens the agreement. They undergo a metamorphosis. The just-hatched young at first hold fast by suction to the jelly of the spawn; they have external gills. They quickly develop a membranous margin to the body, especially round the tail, which consequently forms a sort of oar. Meanwhile internal gills develop, and the external ones disappear. The larvæ are now fish-like (“tadpoles”). The limbs quickly grow out, the lungs develop, the tail shrivels up, and the animal leaves the water. Even the adult, however, lives among damp surroundings. In the adult state the Amphibians feed on insects, worms, and snails; many species are exceedingly useful owing to this.
Amphibians are divided into two orders, the Urodela (Newts, etc.) and the Anura (Frogs and Toads). To the first belong the Great Crested Newt (Triton cristatus) and the Common Newt (Lissotriton tæniatus). Examples of the Anura are the Edible Frog (Rana esculenta), the brownish Common Frog (R. temporaria, Fig. 51), the Common Toad (Bufo vulgaris), and the Natterjack (B. calamita, Fig. 52).
Fig. 51.—Common Frog (Rana temporaria).
Both frogs and toads do good by devouring many noxious insects, and also, in particular, snails. Toads are often kept in greenhouses for this purpose; and in the research garden attached to the Rouen entomological laboratory the snails were entirely exterminated in 1891, as a result of introducing a hundred toads and ninety frogs.
Fig. 52.—Natterjack (Bufo calamita).
Cold-blooded Vertebrates (p. 19), which breathe by gills during their whole life. The heart consists only of a single ventricle and a single auricle (p. 18). The head passes immediately into the body without any intervening neck. Fishes move chiefly by means of the tail, at the end of which there is a tail-fin. This and the dorsal and anal fins lie in the median plane of the fish, while the pectoral fins, which are attached to the skull in bony fishes, and also the ventral fins, are paired structures more or less comparable to the fore and hind limbs of higher vertebrates. The skeleton of most fishes (pike, perch, carp, eel, plaice) is bony; but in a few subdivisions of fishes (sharks, skates, sturgeons, lampreys) it is cartilaginous. The skin is usually covered with thin translucent scales; but there are fishes with a smooth skin (lampreys), with prickle-like dermal ossifications (sharks), and with rhomboidal bony plates (sturgeons). As Fishes are without exception aquatic, there is no need for me to treat more specially of them here.
Fig. 53.—The Perch (Perca fluviatilis).