The genus Sphærospyris differs from all other Spyroidea in the regular spherical or spheroidal form of the lattice-shell. It may therefore be easily confounded with some species of the Sphæroidea; but the internal sagittal ring, placed in the median plane of the fenestrated sphere and connected with it by radial beams, leaves no doubt that it is derived from a true Spyroid, either Dictyospyris or Amphispyris, or another genus. Sometimes also four larger collar pores are visible.

1. Sphærospyris sphæra, Haeckel.

Shell smooth, nearly spherical, slightly flattened at the base, with small regular circular pores. In the centre of the basal plate a regular rectangular cross with four equal collar pores.

Dimensions.—Diameter of the shell 0.11, of the enclosed ring 0.06.

Habitat.—Fossil in Barbados.

2. Sphærospyris quadriforis, n. sp.

Shell rough, nearly spherical, slightly flattened at the base, with small regular circular pores. In the centre of the basal plate a bilateral symmetrical cross with four ovate collar pores; two cardinal pores twice as large as the two jugular pores and six to eight times as broad as the other shell-pores.

Dimensions.—Diameter of the shell 0.26, of the enclosed ring 0.09.

Habitat.—South Atlantic, Station 332, depth 2200 fathoms.

3. Sphærospyris globosa, n. sp. (Pl. 83, fig. 4).

Shell smooth, perfectly spherical, with small subregular circular pores. In the centre of the basal plate no larger collar pores. (The original collar pores are here of the same size as the other pores, and cannot therefore be distinguished.)

Dimensions.—Diameter of the shell 0.13, of the enclosed ring 0.06.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

Genus 485. Nephrospyris,^[103] Haeckel, 1881, Prodromus, p. 444.

Definition.—Androspyrida with a discoidal, kidney-shaped, or subcircular shell, with a basal incision; without transverse constriction and free basal feet.

The genus Nephrospyris is one of the most peculiar and most modified of the Spyroidea, of extraordinary size, in this respect surpassing all other genera of this suborder, and differing from them in its flat discoidal form. The diameter of the compressed shell often reaches one half millimetre or more; its perimeter is elliptical or nearly circular, smooth, constantly with a characteristic deep sternal incision or a basal sinus on the basal pole of the main axis. The central sagittal ring is comparatively small. The margin is often inflated like a delicate reticular girdle, and contains a large number of peculiar spherical or roundish nucleated cells (Pl. 90, figs. 6-10). According to the observations of Dr. John Murray, made on living Nephrospyris, they are Vorticellina, perhaps constant Symbiontes.

Subgenus 1. Nephrodictyum, Haeckel, 1881, Prodromus, p. 444.

Definition.—Network of the shell simple, with bars of nearly equal breadth.

1. Nephrospyris renilla, n. sp. (Pl. 90, figs. 9, 10).

Shell kidney-shaped, one and a half times as broad as long, and three times as long as the deep kidney-shaped sternal incision. Ring with six pairs of branched apophyses, the bars of the apical pair vertical, of the basal pair divergent. The corresponding bars of the two middle pairs (on the frontal and the occipital face) form together on each side a large pentagonal or hexagonal naso-orbital area, which is surrounded by four or five large polygonal meshes; the other meshes become smaller towards the inflated margin. All meshes simple, without arachnoidal framework.

Dimensions.—Shell 0.3 to 0.4 long, 0.4 to 0.5 broad; ring 0.08 to 0.1 long.

Habitat.—Central Pacific, Station 272, depth 2600 fathoms.

2. Nephrospyris nephridium, n. sp.

Shell kidney-shaped, one and two-third times as broad as long, very similar to the preceding species (or only a variety of it?). Ring with seven pairs of branched apophyses. The large naso-orbital area is on the dorsal or occipital side simple, on the ventral or facial side divided by an equatorial pair of transverse horizontal branches into two superior orbital, and two inferior nasal holes. Sternal incision ovate. All meshes simple.

Dimensions.—Shell 0.25 to 0.35 long, 0.4 to 0.5 broad; ring .007 to 0.08 long.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

3. Nephrospyris phaseolus, n. sp.

Shell kidney-shaped, twice as broad as long, very similar to the two preceding species (or only a variety of them?). Ring with eight pairs of branched apophyses. The large naso-orbital area (between the mitral and collar ring) is on the dorsal and on the ventral side divided by two equatorial pairs of horizontal branches into two superior (orbital and occipital), and two inferior (nasal and suboccipital) holes. Sternal incision cordate. All meshes simple.

Dimensions.—Shell 0.25 long, 0.5 broad; ring 0.06 to 0.07 long.

Habitat.—Central Pacific, Station 266, depth 2750 fathoms.

4. Nephrospyris cordata, n. sp.

Shell heart-shaped, about as long as broad. Ring with six pairs of branched apophyses (as in Nephrospyris renilla, Pl. 90, fig. 9). No equatorial transverse branches. Sternal incision cordate, deeper than in all other species of the genus, nearly half as long as the shell. All meshes of the network simple.

Dimensions.—Shell 0.32 long, 0.36 broad; ring 0.05 to 0.06 long.

Habitat.—Central Pacific, Station 263, depth 2650 fathoms.

Subgenus 2. Paradictyum, Haeckel, 1881, Prodromus, p. 444.

Definition.—Network of the shell double; the larger meshes separated by strong bars, and filled up by a very delicate secondary arachnoidal network.

5. Nephrospyris paradictyum, n. sp. (Pl. 90, figs. 1-8).

Shell nearly circular, ten times as broad as the inflated marginal girdle, and three times as long as the sternal incision. Ring with six pairs of branched apophyses; the bars of the apical pair nearly vertical, of the basal pair divergent; the corresponding and opposite bars of the two middle pairs (on the occipital and on the frontal face) form together a large middle naso-orbital area; above and below this lie six pairs of larger meshes. All larger meshes of the network are filled up by very delicate arachnoidal framework. The inflated and delicately reticulated marginal girdle of this and of the following closely allied species is usually filled up by nucleated roundish cells (fig. 7), which are Vorticellinæ, according to the observations of Dr. John Murray on living specimens.

Dimensions.—Diameter of the shell 0.5 to 0.6, of the marginal girdle 0.05 to 0.07; ring 0.07 to 0.09 long.

Habitat.—Central Pacific, Station 271, depth 2425 fathoms.

6. Nephrospyris paradoxa, n. sp.

Shell kidney-shaped, one and one-third times as broad as long, six times as broad as the inflated marginal girdle, and half as long as the sternal incision. Ring with six pairs of apophyses. Above and below the large naso-orbital holes lie ten pairs of larger meshes. All the meshes are filled up by very delicate arachnoidal network.

Dimensions.—Length of the shell 0.4 to 0.5, breadth 0.5 to 0.7; ring 0.06 to 0.08 long.

Habitat.—Central Pacific, Station 270, depth 2925 fathoms.

Suborder II. Botryodea, Haeckel, 1881 (Pl. 96).

Definition.—Nassellaria with a complete lattice-shell, exhibiting constantly a lobate and multilocular cephalis, with three to five or more separated lobes, and two to three or more constrictions.

The suborder Botryodea differs from the other Cyrtellaria in the multilocular and lobate shape of the cephalis, which is composed of at least three or four, often five or six, and sometimes even a greater number of lobes, which are separated by constrictions and partly also by internal septa. This characteristic shape is found neither in the Spyroidea (with bilocular cephalis) nor in the Cyrtoidea (with simple cephalis). The affinities of the former group to the two latter form a very complicated problem, which is not yet solved; the morphology of the Botryodea is the most difficult part in the system of Nassellaria, and what we can here give, are incomplete and unsatisfactory beginnings only.

Up to the year 1860 only a single genus of the Botryodea was known, Lithobotrys, one of the oldest genera of "Polycystina," and described by Ehrenberg in 1844 (Monatsber. d. k. preuss. Akad. d. Wiss. Berlin, p. 74). He gave the following definition:—"Loricæ siliceæ articuli in adulto non in seriem, sed in uvæ brevis formam, id est in loculos plus minus discretos nonnullos contiguos dispositi. Proxime ad Lithocampem accedit." In his first System (1847) Lithobotrys is placed with Lithocampe among his family Lithochytrina. Afterwards (1860) Ehrenberg added two new genera, under the names Botryocampe and Botryocyrtis and figured some species of these incompletely in his last works (1872, 1875).

In my Monograph I founded for these three genera the separate subfamily of Polycyrtida, added as a fourth genus Spyridobotrys, and gave to the group the following definition (1862, loc. cit., p. 341):—"Lattice-shell divided by two or more annular strictures, partly longitudinally, partly transversely, into three or more unequal chambers, which are placed in different planes and have a different relation to the poles of the shell-axis."

The new and remarkable forms of Botryodea, which I subsequently found in the Challenger collection, demonstrated that the Botryodea differ from the other Cyrtellaria (the Cyrtoidea as well as the Spyroidea) in a far higher degree than I formerly had supposed. A synopsis of the figures in Pl. 96 will give sufficient evidence of this view. Therefore in my Prodromus (1881, p. 439) I completely separated the Botryodea (or Botrida) from the other suborders of Cyrtellaria (Spyrida and Cyrtida).

Bütschli gave, in 1882, in his paper on the Cyrtida (loc. cit.) a very accurate description of Lithobotrys geminata, and pointed out its close affinity to Lithocorythium and Lithomelissa, and the importance of an oblique septum separating the cephalis into a smaller anterior and a larger posterior lobe. His views on the Botryodea (as a subordinate group of the Cyrtoidea) are however incomplete, since the peculiar forms, described in the following pages, were unknown to him.

According to the wide morphological divergence of the different Botryodea, and the numerous peculiar forms developed from it, we here divide the whole group into three families and ten genera, with fifty-five species. These form, however, only a small part of the large and varied mass of closely related forms which are found in the rich collections of the Challenger. The great difficulty of researches on their intimate structure, and the great amount of time required for it, prevented me from giving a more complete and exact description than the one here given. The observation of the small shells from all the different sides is a difficult task, requiring years of work, and its satisfactory explanation would be possible only by means of numerous figures.

The three families of Botryodea, here described, correspond to the three first groups of Cyrtoidea. The first family, Cannobotryida, corresponds to the Monocyrtida clausa and to the Zygospyrida; their shell consists of a cephalis only, without subsequent joints. The second family, Lithobotryida, corresponds to the Dicyrtida and Phormospyrida; their shell is composed of a cephalis and a thorax, both joints being separated by a transverse cortinar septum and a collar stricture. The third family, Pylobotryida, has a three-jointed shell, like the Tricyrtida, with cephalis, thorax and abdomen.

The cephalis is the most characteristic part of the shell of the Botryodea and its lobulate and multilocular shape separates them from the Spyroidea and Cyrtoidea. It represents the whole shell in the Cannobotryida, and in the young state of the two other families, which afterwards develop a thorax (Lithobotryida) and an abdomen (Pylobotryida). The typical lobulation of the cephalis is probably originally caused by internal septa; and these may be originated by branches of the internal columella, which corresponds either to the central ascending columella of the Plectoidea or to the excentric ascending dorsal rod of the sagittal ring of the Stephoidea. But afterwards, when the original septa disappear and are lost by reduction, only the external constrictions remain to indicate the limits of the single lobes.

Among the internal septa and the corresponding external constrictions which effect the lobulation of the cephalis, may be distinguished primary or constant septa and secondary or inconstant septa. As primary septa we regard firstly an oblique frontal septum and secondly a vertical sagittal septum. The frontal septum (described accurately by Bütschli) has usually two or three pairs of pores and ascends obliquely from the base to the anterior face of the cephalis, where it is inserted in the orbital region; it divides the cephalis into a smaller anterior or facial lobe and a larger posterior or occipital lobe. The latter is commonly higher and more developed than the former and partly covers its upper face, like the crest of a helmet. The facial lobe is again bisected by an incomplete sagittal septum and a corresponding partial constriction on the anterior face. We find, therefore, in this original cephalis of the Botryodea, three primary lobes, an odd larger occipital lobe and two paired smaller facial lobes. The typical trilobed cephalis may be regarded perhaps as the common original form of the Botryodea.

The secondary and inconstant constrictions which we find in many Botryodea, and which produce a greater number of lobes in the cephalis, require further accurate observation. The following cases of lobation may be considered as the most important:—(1) Cephalis with four lobes, opposite in two pairs (two larger occipital and two smaller facial lobes, separated by a complete sagittal and an oblique frontal constriction); (2) cephalis with four unequal lobes, two of which are odd and sagittal, two paired and lateral (the odd occipital lobe usually larger and the odd mandibular lobe smaller than the two paired lateral or buccal lobes); (3) cephalis with five lobes (a large odd occipital lobe and two pairs of smaller lobes, anterior nasal, and lateral buccal lobes); (4) cephalis with five lobes, three of which are odd (a posterior occipital, middle frontal, and anterior facial lobe), and one pair of lateral lobes; (5) cephalis with six lobes, opposite in pairs (two larger occipital, two smaller nasal and two intermediate lateral or buccal lobes); (6) cephalis with six lobes, two of which are odd and sagittal (a large occipital and a smaller nasal lobe), four opposite in pairs (two anterior and two posterior buccal lobes); (7) cephalis with seven lobes, three of which are odd (a large posterior occipital, a middle frontal, and an anterior small nasal lobe), four opposite in two pairs (an anterior buccal and a posterior temporal pair); (8) cephalis with eight lobes, two of which are odd (a large posterior occipital and a small anterior frontal lobe) and six opposite in three lateral pairs; (9) cephalis with nine lobes, three of which are odd (an occipital, a frontal and a nasal lobe) and six opposite in three lateral pairs; (10) cephalis with ten lobes, two of which are odd (a large occipital and a smaller frontal lobe) and the other eight opposite in pairs; (11) cephalis with numerous lobes (twelve to fifteen or more) which are symmetrically disposed on each side of the median plane; (12) cephalis with numerous lobes (twelve to fifteen or more) which are irregularly and sometimes spirally conglomerated.

All these different forms of lobation require a far more thorough examination than I can devote to them, and may furnish examples of regular laws of development. The irregular forms are rather common, and I have found some very irregular Botryodea (not here described) in which I could not determine the topographical regions of the cephalis. The difficulty in the examination of these complicated forms is increased by their very small size, which does not reach the usual dimensions of the other Cyrtellaria. In some cases I was able to observe on the base of the cephalis the same typical cortinar pores (in two or three pairs), which we also find in the same part of the cephalis in the Spyroidea and Cyrtoidea, and which are inherited from the Semantida.

The thorax of the Botryodea, or the second shell-joint, absent in the Cannobotryida, is usually of very simple form, ovate, truncate, conical or cylindrical, and consists of a secondary joint, developed from the base of the cephalis. The thorax is usually small, about the same size as the cephalis or a little larger, whilst in the Cyrtoidea it is commonly much larger than the latter. Its terminal mouth is closed by a lattice-plate in the Botryocellida, while it remains open in the Botryopylida and Pylobotryida.

The abdomen, or the third shell-joint, developed in the Pylobotryida only, generally also exhibits a very simple shape, like the thorax, and it is a tertiary joint developed from the base of the thorax. It exhibits to the latter the same relation as in the Tricyrtida. The terminal mouth of the abdomen remains open in the Botryocyrtida; it becomes closed by a lattice-plate in the Botryocampida.

The lattice-plate forming the shell of the Botryodea is usually very thin and fragile, with very small circular pores. These are often very numerous, at other times scarce, and sometimes nearly wanting, so that the shell appears hyaline. In this group there never occurs that great variety in form and size of the pores, which numerous Cyrtoidea and Spyroidea exhibit.

The radial apophyses which are found in the majority of Botryodea seem to correspond in position and relation to the typical radial beams of the other Nassellaria, viz., three descending basal feet arising from the base of the cephalis, and an ascending vertical apical horn arising from the top of the cephalis. Here also they seem to be inherited from the Plectoidea or Stephoidea (Cortina, Cortiniscus). But whilst these four typical radial beams in the other Nassellaria are usually simple spines or solid rods, here they usually appear as hollow cylindrical tubes, the thin wall of which is pierced by the same small pores as the shell. These porous tubes are either straight or slightly curved, often inflated and ovate at the base. We find in their number and disposition the same variety as in the simple radial spines of the other Nassellaria. The original number may here also be seen in the development of four typical beams, an ascending apical tube on the top of the cephalis, and three descending basal tubes on its base; the odd posterior tube of the latter corresponds to the caudal foot, the two paired anterior to the pectoral feet. There is often also a fourth foot developed opposite to the caudal, and representing a sternal tube. Sometimes also two superior tubes are developed, a posterior occipital and an anterior frontal. The different apophyses may be lost by reduction. I have never observed Botryodea with more than five apophyses.

The Central Capsule of the Botryodea is not yet sufficiently known, no living species having been observed. In some preparations from specimens in the Challenger collections, stained by Dr. John Murray with carmine immediately after the dredging operation, single Botryodea are to be found in which the central capsule is deeply coloured. In Botryopera quinqueloba (Pl. 96, fig. 2) it filled up the greater part of the cephalis and seemed to be divided into some small lobes. In Lithobotrys sphærothorax (Pl. 96, fig. 15) it was divided into four lobes, three of which filled the trilobed cephalis, the fourth large lobe occupying a great part of the spherical thorax. Details of their structure, unfortunately, were not recognisable. There can, however, be no doubt that they are the same as in all other Nassellaria.

Synopsis of the Families of Botryodea.

Family LVI. Cannobotryida, Haeckel (sensu emendato).

Definition.—Botryodea monothalamia, the shell of which represents a lobate cephalis, without thorax and abdomen.

The family Cannobotryida (retained here with a stricter definition than originally was given in my Prodromus) comprises those Botryodea, in which the whole shell is represented by the cephalis alone, without thorax and abdomen. Since the two latter joints, found in the two following families, are secondary productions, the Cannobotryida must be regarded as the ancestral forms of all Botryodea, in an ontogenetic as well as in a phylogenetic sense.

Two species only of this family have been hitherto known, incompletely described by Ehrenberg as Lithobotrys triloba and Lithobotrys quadriloba. A great number of similar forms are to be found in the Radiolarian ooze of the Central Pacific, but they are very minute, and difficult to examine. We can describe here only twelve species of these, which we arrange in two genera; Botryopera without porous tubes, and Cannobotrys bearing a variable number of porous cylindrical tubes (one to five). The number of lobes of the cephalis is also variable in each genus (one to five or more). If in the future these minute and interesting shells should be better examined, it would be advisable to distinguish a number of genera according to the different number of the porous tubes and of the lobes of the cephalis. The base of the latter is constantly closed by a basal lattice-plate, and usually exhibits two or three pairs of cortinar pores, identical with those of the Semantida.

The phylogenetic origin of the Cannobotryida may be found either in the Zygospyrida or in the Monocyrtida; they differ from these two similar groups in the lobation of the cephalis, which is effected by the development of internal septa and external constrictions.

Synopsis of the Genera of Cannobotryida.

Genus 486. Botryopera,^[104] n. gen.

Definition.—Cannobotryida without tubes on the cephalis.

The genus Botryopera is the simplest form among the Botryodea, the shell consisting of a lobate cephalis only, without tubes or radial appendages. It may be derived either from Dictyospyris or from Archicapsa by development of the horizontal fold in the frontal face of the shell, and the corresponding internal frontal septum, which separates the larger occipital lobe from the smaller facial half; the latter may be divided again into paired frontal lobes, lateral buccal lobes, &c. Botryopera may be the common ancestral form of many Botryodea.

1. Botryopera cyrtoloba, n. sp. (Pl. 96, fig. 1).

Cephalis trilobate; the posterior odd occipital lobe helmet-shaped, about twice as large as the two paired anterior frontal lobes, which are subovate and covered by the upper half of the former. Pores small and numerous, subregular, circular; some larger pores at the base.

Dimensions.—Length of the shell 0.08, basal breadth 0.06.

Habitat.—Central Pacific, Station 265 to 274, depth 2350 to 2925 fathoms.

2. Botryopera triloba, Haeckel.

Cephalis trilobate; the occipital lobe subcylindrical, one and a half times as long as the two frontal lobes, which are slender, ovate and not covered by the former. Pores small and numerous.

Dimensions.—Length of the shell 0.05, breadth 0.03.

Habitat.—Fossil in Tertiary rocks of the Mediterranean (Sicily, Greece, &c.)

3. Botryopera quadriloba, Haeckel.

Cephalis quadrilobate; the occipital lobe helmet-shaped, one and a half times as long as the two paired hemispherical buccal lobes, and twice as large as the anterior frontal lobe. Pores not numerous, rather large, circular.

Dimensions.—Length of the shell 0.06, breadth 0.04.

Habitat.—Fossil in Barbados and North America (Virginia).

4. Botryopera quinqueloba, n. sp. (Pl. 96, fig. 2).

Cephalis quinquelobate; the occipital lobe helmet-shaped, and twice as long as the two hemispherical frontal lobes, three times as long as the subspherical lateral buccal lobes. Pores scarce, small, circular.

Dimensions.—Length of the shell 0.07, basal breadth 0.05.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

5. Botryopera multiloba, n. sp.

Cephalis multilobate; the posterior odd occipital lobe ovate, and of about the same size as the anterior frontal half of the shell, which is clustered and divided into five to seven smaller lobes, an odd subspherical sternal lobe, and on each side of it two or three pairs of smaller subspherical lobes.

Dimensions.—Length of the shell 0.09, breadth 0.06.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Genus 487. Cannobotrys,^[105] Haeckel, 1881, Prodromus p. 440.

Definition.—Cannobotryida with tubes on the cephalis.

The genus Cannobotrys differs from the preceding Botryopera in the development of hollow radial tubes, arising from the lobate cephalis in various numbers. According to their number the genus may be divided into various subgenera: (1) Cannobotrantha (monocanna) with a single apical tube; (2) Cannobotrella (dicanna) with two divergent tubes, an ascending apical and a descending sternal one; (3) Cannobotrissa (tricanna) with three tubes in the sagittal plane (an upper apical, a posterior caudal, and an anterior sternal); (4) Cannobotromma (tetracanna) with four radial tubes disposed like the four typical spines of Cortina (compare p. 950), and Cannobotrusa (pentacanna) with five radial tubes disposed like the five typical spines of Stephanium (p. 952). Perhaps these five groups may be separated as five genera, possessing near relations to five very different genera of Nassellaria (Circospyris, Halicapsa, Archibursa, Cortina, Stephanium, &c.)

1. Cannobotrys monocanna, n. sp.

Cephalis trilobate, with a single cylindrical straight apical tube on the apex of the occipital lobe, which is helmet-shaped, and about one and a half times as long as the two subspherical frontal lobes. Pores small and numerous, subregular, circular.

Dimensions.—Length of the shell 0.05, breadth 0.03.

Habitat.—Tropical Atlantic, Station 347, depth 2250 fathoms.

2. Cannobotrys dicanna, n. sp.

Cephalis quadrilobate, with two divergent tubes, an odd apical tube on the apex of the posterior occipital lobe, and an odd sternal tube on the anterior frontal lobe. Between these two odd lobes lie two paired lateral or buccal lobes, of about the same size. Shell nearly hyaline, with very few minute pores.

Dimensions.—Length of the shell 0.06, breadth 0.04.

Habitat.—Indian Ocean; Madagascar (Rabbe), surface.

3. Cannobotrys tricanna, n. sp. (Pl. 96, fig. 3).

Cephalis quinquelobate, with three curved cylindrical tubes in the sagittal plane; an ascending apical tube on the apex of the helmet-shaped occipital lobe, and two horizontal tubes on the base of the shell (a posterior caudal, c, and an anterior sternal, z). The two frontal lobes are hemispherical, and twice as large as the two lateral buccal lobes. Pores very small and numerous.

Dimensions.—Length of the shell 0.08, basal breadth 0.06.

Habitat.—Central Pacific, Station 265, depth 2900 fathoms.

4. Cannobotrys sagittalis, n. sp.

Cephalis multilobate, with three straight divergent cylindrical tubes in the sagittal plane; a vertical apical tube on the apex of the ovate occipital lobe, and two horizontal tubes on the base, as in the preceding similar species; it differs from the latter in the greater number of lobes (seven or nine), the two frontal lobes being divided into two or four secondary lobules.

Dimensions.—Length of the shell 0.1, breadth 0.07.

Habitat.—Central Pacific, Station 274, depth 2750 fathoms.

5. Cannobotrys cortina, n. sp. (Pl. 96, fig. 4).

Cephalis quinquelobate, with four cylindrical nearly straight tubes of equal size; an ascending, nearly vertical, apical tube on the apex of the occipital lobe, and three divergent descending tubes on the base of the shell (an odd posterior caudal tube and two paired anterior pectoral tubes). The two lateral buccal lobes are twice as large as the two anterior frontal lobes, and half as large as the posterior odd occipital lobe. The four tubes in this and the following species correspond probably to the four spines of Cortina (p. 950).

Dimensions.—Length of the shell 0.07, basal breadth 0.06.

Habitat.—Central Pacific, Stations 263 to 274, depth 2350 to 2925 fathoms.

6. Cannobotrys tetracanna, n. sp.

Cephalis multilobate, with four cylindrical curved tubes conical at their wider base, corresponding to those of the preceding species and to the four spines of Cortina. The odd occipital lobe is of about the same size as the anterior part of the shell, which is cleft into three pairs of roundish lobes, one pair of anterior larger frontal lobes, and two pairs of smaller lateral buccal lobes. Pores very few and minute.

Dimensions.—Length of the shell 0.11, basal breadth 0.07.

Habitat.—North Pacific, Station 253, depth 3125 fathoms.

7. Cannobotrys pentacanna, n. sp.

Cephalis quinquelobate, with five cylindrical slender curved tubes, three of which are placed in the sagittal plane (a superior apical, a posterior caudal, and an anterior sternal), whilst the other two are paired and diverge laterally (two pectoral tubes). The five tubes correspond exactly to the five typical spines of Stephanium (p. 952). The helmet-shaped occipital lobe of the shell is twice as large as each of the two anterior frontal lobes, and three times as large as each of the two lateral buccal lobes. Pores numerous.

Dimensions.—Length of the shell 0.07, basal breadth 0.04.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.

Family LVII. Lithobotryida, n. fam.

Definition.—Botryodea dithalamia, the shell of which is composed of a lobate cephalis and a simple thorax, without abdomen.

The family Lithobotryida comprises those Botryodea in which the shell is divided by a transverse annular constriction into a lobate cephalis and a simple thorax. They correspond therefore to the Dicyrtida among the Cyrtoidea, and to the Phormospyrida among the Spyroidea. The thorax, or the second shell-joint, is in all these three families a secondary production, arising from the base of the cephalis; therefore the Lithobotryida must be phylogenetically derived from the Cannobotryida.

Several species of Lithobotrys were first described by Ehrenberg as Lithobotrys and Lithocorythium. These two genera are, however, identical, as has been demonstrated by Bütschli (1882, loc. cit., p. 519). Some other species united by Ehrenberg with Lithobotrys belong to other genera. The number of Lithobotryida found in the "Radiolarian ooze" of the Challenger collection, is far greater than that of the Cannobotryida and Pylobotryida. But only a small part of them could be thoroughly examined and described here, so that their number may be greatly augmented by further accurate researches. We here arrange those forms in four genera, representing two different subfamilies. The terminal mouth of the thorax remains open in the Botryopylida, whilst it becomes closed by a lattice-plate in the Botryocellida. In each group there are shells with and without porous tubes. The number of these tubes, and also the number of lobes of the cephalis, is very variable, and may in future serve for the distinction of more genera.

Synopsis of the Genera of Lithobotryida.

Genus 488. Botryopyle, Haeckel, 1881, Prodromus, p. 440.

Definition.—Lithobotryida without tubes on the cephalis, and with the mouth of the thorax open.

The genus Botryopyle comprises the simplest forms of Lithobotryida, the lobate cephalis bearing no tubes and the basal mouth of the thorax remaining open. It may be derived either from Dictyocephalus or from Desmospyris, by development of lobes on the cephalis and of an internal frontal septum, separating the larger occipital lobe from the smaller frontal half of the shell. The latter may be divided again into anterior frontal lobes, lateral buccal lobes, &c.

1. Botryopyle sethocorys, n. sp. (Pl. 96, fig. 7).

Cephalis trilobate, separated by a deep collar constriction from the hemispherical thorax, which is twice as broad. Occipital lobe helmet-shaped, little longer than the two hemispherical frontal lobes. Surface spiny. Pores irregular, roundish, of very different size.

Dimensions.—Length of the shell 0.1, breadth 0.07.

Habitat.—Western Tropical Pacific, Station 225, depth 4475 fathoms.