THE ANATOMY OF PLEUROTOMARIA BEYHICFIII. 267 



Fig. 27. — Diagram of the nervous sj'steni viewed from above. 



Fig. 28. — Dissection of the head, foot, and mantle, showing the relations 

 of the nervous system on tiie right side of the body ; also the anterior aorta 

 and supra-neural and pedal artery. 



Fig. 29. — Enlarged view of the brain, cerebro-i)leural, and cerebro-pedal 

 connectives, and the relation of the nerves to the lips and buccal mass. 



Fig. 30. — A — //. Eight views of the musculature of the buccal mass. J. 

 Dorsal view. B. Side view, with the lateral protractor {l.pr.) reflected. C. 

 Ditto, with the ventral longitudinal muscle {v. l.m.) reflected. D. Ditto, after 

 the removal of the lateral longitudinal, the radula, and greater part of the 

 iufra-radular membrane {i.r.vi.). E. Ditto, after the removal of the main 

 odontophoral cartilage, exposing the internal longitudinal muscle {i. I. »/.). 

 F. Dorsal dissection, showing the cartilages on the left, and the muscles and 

 infra-radular membrane on the right. G. Viewed from below, showing the 

 transverse muscle {v.i.m.). H. Diagrammatic transverse section. 



F'iG. 31. — A. Entire otocysts. x 50. B. Isolated otoconia. X 400. 



PLATE 10. 



Fig. 32. — Half a transverse row of teelli, including the rhachidiaii. x 50. 



Fig. 33. — Rhachian tooth, side view, x G6. 



Fig. 34. — First central tooth, side view, x 66. 



F'iG. 35. — Second central tooth, side view, x 66. 



Fig. 8G. — Third central, with first and second lamellate tooth. X 66. 



I'lG. 37. — Four views of a typical lamellate tooth, from the left side of 

 the radula. //. Viewed from the outer side. B. Normal view. C. Edge on. 

 D. Viewed from below, x 140. 



Fig. 38.— Twenty-lifth tooth, x 60. 



Fig. 39. — Twenty-sixth tooth, x 60. 



I'iG. 40. — Twenty-seventh tooth, x 60. 



Fig. 41.— Thirtieth tooth, X 60. 



Fig. 42.— Thirty-fourth tooth, x 60. 



F'iG. 43. — Thirty-seventh tooth, x 60. 



F'iG. 44.— Thirty-ninth tooth, x 60. 



Fig. 45. — Forty-second tooth, x 120. 



Fig. 46.— Forty-third tooth, x 120. 



Fig. 47.— Forty-fourth tooth, x 120. 



Fig. 48.— Forty-seventh tooth, x 120. 



Fig. 49.— Forty-ninth tooth, x 120. 



Fig. 50. — Type of tooth between the fiftieth and the sixtieth, x 120. 



