204 J. E. S. MOORE. 



Fig. 36. — Ot.ocyst in section, showing sensory epithelium and otoliths and 

 sensory processes, 1. 



Fig. 37. — Section through, showing ganglionic character of the right 

 visceral cord at the point marked x' in Fig. 35. 



Fig. 38. — Sectiou through cerebral ganglion in the region of the otocyst 

 nerves. 



Fig. 39. — Sensory epithelium of the otocyst in surface view. 



Fig. 40. — Section through anterior pedal nerves and ganglion, showing the 

 ladder-like connection between the roots of the anterior pedal nerves. 



Fig. 41. — Section through snout, showing the buccal ganglia. 



PLATE 14. 



Fig. 42. — Semi-diagrammatic representation of the alimentary canal of 

 Typhobia Horei. 1. (Esopliagus. 2. Opening oi' the oviduct. 3. Ova 

 in ovisac. 4. Rectum. 5. Stomach. 6. Opening of the ffisophagus into the 

 stomaeli. 7. Pyloric aperture. 8. Crystalline style. 



Fig. 43. — A single row of teeth from the radula of Typhobia Horei. 



Fig. 44. — Dissection of the stomach. 1. Bristle passed through the 

 opening of the oesophagus into the stomach. 2 and 3. Ditto, passed through 

 the opening of the bile-ducts into the stomach. 4. Bristle passed through 

 the pyloric aperture into the stomach. 5. Crystalline style. 6. Intestine. 

 7. Median fold in stomach. 8. Smaller fold. 9. Constricted annulus dividing 

 the stomach proper from the eaicum containing the crystalline style. 



Fig. 45. — Rectum and genital aperture in the male. 1. Buccal mass. 

 2. Anus. 3. Genital aperture. 4. Penis. 5. Glandular folds in the cavity 

 of the rectum. 



Fig. 46. — Same. 1. Penis opened to show the muscular core. 



Fig. 47. — Illustrating the course of the oviduct in a female. 



Fig. 48.— Heart dissected. 1. Cavity of ventricle. 2. Auricle. 3. Auri- 

 cular ventricular valve. 4. Valve between the ventricle and the aortic trunk. 

 5 and 6. Openings into the anterior and posterior aorta. 7 and 8. Anterior 

 and posterior aortse. 



l^'iG. 49. — Dissection of male, showing : — 1. Enlargement of rectum. 



2. Gills. 3. Penis. 4. Anus. 5. Genital aperture. 6. Enlargement of 

 lower extremity of vas deferens, with parallel folds. 7. Upper portion of the 

 vas deferens. 



Figs. 50 — 53. — Semi-diagrammatic representation of the stomachs and 

 crystalline styles in Lithoglyphus, Typhobia, Pterocera, and Lutraria. 



Fig. 54. — Male genital apparatus dissected out. 1. Aperture. 2. Anus. 



3. Penis. 4. Vas deferens. 5. Collecting tubes. 6. Testes. 



