PLATE VTTT. 



C. sibogae. 



Figs. 80 — 89. — Male. 



Figs. 90 — 93. — Neuter. 



Fig. 94. — Common stalk-base. 



Figs. 80 — 89. — Frontal sections of the male shewn in I'l. VII, tig. 75. For explanation, see text, p. ^6. 



Fig. 80. — Through dorsal lobe of proboscis (/.). The arms (L.a., R.a.) are somewhat macerated. 



Fig. 81. — Through region of pericardium (7 sections later). 



Fig. 82. — The ne.xt section. 



Fig. 83. — The ne.xt section but one. 



Fig. 84. — Through the mouth (3 sections later). 



Fig. 85. — Two sections later. 



Fig. 86. • — Three sections later. 



Fig. 87. — Three sections later. 



Fig. 88. — Two sections later. 



Fig. 89. — Forty four sections later. 



Figs. 90, 91. ■ — Frontal sections of a neuter. 



Fig. 90. — Through the entire length of the right gill-slit (g. s.) : — //., plcurochordal tissue of groove 

 continuous with the left gill-slit and the left pleurochord. 



Fig. 91. — Five sections nearer the stalk, cutting both pleurochords (pL). 



Fig. 92. — Obliquely frontal section of another neuter, cutting the posterior end of the ventral side of 

 the collar. The arms of this specimen are shewn in PI. IX, fig. 97. 



F'g- 93- — Obliquely frontal section of the anterior end of a neuter. The left arms have been broken 

 off, a torn place in the section marked L.a. indicating part of their base. The section shews the 

 strong muscles {ins.) of the metasome inserted into septum "/,, from which starts one of the 

 origins of the large oral muscle (or. in.). The wall of the gill-slit [g.s.) is composed of pleurochordal 

 tissue. The ventral epithelium of the collar-canal (c.c.) is strongly ciliated. The problematical tissue 

 (x.) of the collar-canal has a distinct row of nuclei on its coelomic border, while a band of muscle 

 passes from it across the collar-cavity to the basement-membrane of the epidermis. 



Fig. 94. — Common-base of stalks, in vertical section. 



[Fig. g.f. tuns drawn witli ZEISS DD Obj.; 80 — c^j with C Obj. None of the drazvings have been reduced]. 



