PLATE IX. 



Figs. 95 — 99, I02, 103. — C. sibogae. 

 Figs. 100, 10 1, 104 — iio. — C. levinscni. 



Fig. 95, 96. C. sibogae. — Two views (ZeisS, C) of the anterior part of the male shewn in PI. VII, fig. j6. 



Fier. 05. Anterior view. The ventral lobe (/'.) of the proboscis is turned forwards, exposing the mouth 



(w.), on each side of which is seen a collar-canal (f. r.). The mouth leads to a vestigial ahmentary 

 canal, the intestinal limb of which is marked ;-. R.a. and L.a., right and left arms; t.r.,t.l., 

 right and left testes. 



Pier. 06. Posterior view of the same specimen: — c.n.s., swelling of collar due to the presence of the 



central nervous system; g.p. appears to be one of the generative pores; d.v., dorsal vessel; 

 r., intestinal limb of alimentary canal. 



Fio-. 97. C. sibogae. — Frontal section of anterior end of the specimen shewn in PI. VIII, fig. 92, shewing 

 the proboscis (/.), and the four pairs of arms (Zeiss, C). 



Fio-. 98. C. sibogae. — Abnormal arm of a tentaculiferous individual, the distal end of which is produced 

 into a long vesicle-bearing portion, resembling the arm of a male (Zeiss, C). The arm may 

 belong to the first pair, but this is uncertain. The individual to which this arm belongs appears 

 to have a pair of testes, in the position of the ovaries of a female Ceplialodiscus. The testes, 

 though small, seem to be functional. The specimen in other respects resembles a normal neuter: — ■ 

 tent., tentacles. 



Fig. 99. C. sibogae. — Base of arm of a young male, partly in optical section, shewing the characteristic 

 epidermic vesicles, which do not occur in the proximal region of the arm (Zeiss, D D). 



Fier. 100. C. levinseni. — Obliquely sagittal section of a young individual (Zeiss, C). The proboscis-stalk 

 is strongly contracted and bent, as is indicated by the fold (/.) of its dorsal body-wall: — 

 rt.', one of the first arms. 



Fi". lOi. C. levinscni. — Lateral sagittal section of an old individual with reversed proboscis (Zeiss, C): — 

 ƒ.,ƒ., folds of body-wall of proboscis which appear to indicate the region where the rotation 

 has been effected. 



Fio-. 102. C. sibogae. — Section of part of the basal encrustation of the coenoecium (Greenough bino- 

 cular, a-.). The letters indicate the corresponding parts in fig. 103. 



Fig. 103. C. sibogae. — Part of fig. 102, more highly magnified (Zeiss, A). For explanation of lettering, 

 see text, p. 15; ^i,"", a secondary lamella. 



Figs. 104 — 106. C. levinseni. — Sagittal sections of an embryo (Zeiss, C). 



Fig. 104. — Lateral section, shewing the dorsal vacuolated ectoderm (vac), the ventral thickening {v. t.) 

 and the three body-cavities [b.c.'^'^). 



Fig. 105. — Nearer the middle line: — the yolk-mass {yk) is divided into three portions. 



Fig. 106. — More median region: — s.o., sense-organ (?), which appears as an invagination of the vacuo- 

 lated ectoderm (vac.). The two principal divisions of the yolk-mass are less clearly seen hcre 

 than in some of the figures on PI. XIV: an. is probably the future anus: b.cr is visible on the 

 dorsal side of the yolk-mass. 



Fig. 107. C. levinseni. — Transverse section through the ventral border of the collar and part of the 

 metasome (ZeisS, D D). The operculum [op.] is directed forwards, and appears emarginate in the 

 middle line: — v.mes."^, ventral mesentery of collar; v.vies.^. of metasome; s."^]^, trunco-collar 

 septum; ni., level of mouth; b.)n., basement-membrane of oral epidermis of operculum, with muscles. 



Fig. 108. C. levinseni. — Transverse section of a peristome (Zeiss, A) : — ;«.;'., mid-rib; pr.L, primary 

 lamellae. 



Fig. 109. C. levinseni. — Transverse section through an entire branch of the coenoecium (GREENOUGH 

 ' binocular, a.-). The letters indicate the corresponding parts in fig. iio. 



Fig. iio. C. levinscni. — Part of fig. 109, more highly magnified (ZEISS, A): d, e, f, cavities of zooecia; 

 py. /., primary lamellae. For other letters, see text, p. 10. 



\All tlie figures have been reduced -/j]. 



