26 " ARTHUR E. SHIPLEY. 



Fig. 8. — A transverse section through the head in the region of the brain, 

 The introvert is everted. This specimen had its body wall pushed upwards 

 inside the lower lip in the ventral side into a kind of hernia, this accounts for 

 the swelling containing blood-corpuscles and sperm-morulse. The brain is 

 shown in its sinus, also the depressions in the tissue of prseoral lobe leading 

 to the sensory pits. 



Fig. 9. — A transverse section through the oesophagus. The dorsal and 

 ventral retractor of each side have fused into a common lateral muscle, which 

 almost fills up the body-cavity. The lumen of the oesophagus is occluded by 

 ciliated ridges. 



Fig. 10. — A section through the ectoderm and cuticle. Below the ectoderm 

 some fibres of the circular muscle may be seen. The ectoderm is vaulted 

 leaving spaces which sometimes contain a coagulable fluid. Tlie cuticle is 

 traversed by numerous perpendicular lines, and the outer part only stains. 



Fig. 11. — A surface view of the skin, showing the longitudinal and circular 

 muscle-fibres, the skin papillae, and the ridges formed by thickenings of the 

 cuticle. 



Fig. 12. — A section of one of the sense organs on the introvert, at the 

 base of the ring of hooks. 



Fig. 13. — A transverse section through the posterior end of the animal. 

 The longitudinal muscles have fused together and reduced the lumen of the 

 body-cavity to a star-shaped mass. The skin papilla3 are very numerous in 

 this region, and the cuticle unusually thick. 



PLATE III. 



Fig. 14. — Section taken through one of the skin papilla; of the trunk. It 

 shows the opening to the exterior, and the small cavity in the cup composed of 

 enormous cells crowded with spherules. 



Fig. 15, — Surface view of the papillae and hooks in the introvert. The 

 chitinous plates round the orifice of these papillae are shown. 



Fig. 16. — An oblique section through a trunk papilla. This section shows 

 the space between the two layers of the cup in communication with the sub- 

 ectodermal spaces of the skin. 



Fig. 17. — Transverse section of a tentacle. At the base of the ciliated 

 groove the tentacular nerve lies. Three blood-spaces are seen, and between 

 them certain skeletal cells. The inner epithelium is crowded with pigment 

 grains. 



Fig. 18. — A diagram showing the anatomy of the nephridium. The pos- 

 terior blind diverticulum is the secreting part, the anterior thin-walled part is 

 the bladder. The arrangement of the internal and external openings may 

 also be seen. 



Fig. 19. — An oblique section through the secreting part of the nephridium, 

 under a low power. This shows the peritoneal epithelium, then a dark 



