98 ARTHUli 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-morulae. 

 The brain is shown in its sinus, also the depressions in the tissue of 

 prteoral lobe leading to the sensory pits. 



Fig. 9. — A transverse section through the cEsophagus. 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. The 

 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 thicken- 

 ings 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 papillse 

 are very numerous in this region, and the cuticle unusually thick. 



PLATE IX. 



Fig. 14. — Section taken through one of the skin papillse of the trunk. 

 It shows the opening to the exterior, and the small cavity in the cup 

 composed of euormous cells crowded with spherules. 



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

 chitinous plates round the orifice of these papillse 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 

 posterior 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 nephri- 

 dium, imder a low power. This shows the peritoneal epithelium, then a 



