64 WALTER K. FISHER, 



Fig. 12. Cross section of duct of buccal or anterior salivary gland, 

 much enlarged. 



Fig. 13. Buccal cartilages, showing muscles which fasten lateral 

 cartilages (lat.c) to the pair of fused median ones (med.c). 4: 1. 



Fig. 14. Radula teeth, much enlarged. 



Fig. 15. Section of epithelium from subradular organ, showing 

 teeth, pointing forward ; much enlarged. 



Fig. 16. Dorsal view of buccal mass to show retractors of radula 

 (see text). 4 : 1. 



Fig. 17. Stomach: most of the dorsal wall has been taken off to 

 show raised stripe of epithelium, and opening of the liver duct. 



li/ 2 :l. 



Fig. 18. Lips, seen from below. Enlarged three times (3 : 1). 



Plate 2. 



Fig. 19. Drawn to show circulation in mantle, and venous circu- 

 lation of foot, seen from below. The head has been removed to 

 show the mantle hood. The circumpallial vessel is red, while the veins 

 emerging from the foot and spreading out on the mantle are in blue. 

 Enlarged slightly over. 2:1. 



Fig. 20. Dorsal view of animal with shell, and portion of mantle 

 hood (Ma 1 ) removed. The right nephridium is in blue, and the small 

 left one in red. That portion of the right nephridium in blue also in- 

 cludes the area of the vein-net of blood vessels. The arm of the gonad, 

 which leads to the gonoduct is shown behind the pericardium. Natural 

 size, large individual. 



Fig. 21. Dorsal view, with sections of the stomach and intestine 

 removed to show the arterial circulation in visceral mass. (The 

 branches of the genital artery lie beneath these and are not shown.) 

 The whole anterior loop of the stomach, the rectum, and a bend of the 

 alimentary canal just beyond stomach have been taken out. The dorsal 

 branch (Dors. Br) of the visceral artery is not shown. A section of 

 the kidney vein-net, and kidney collector (blue) are drawn in on the 

 left. 2:1. 



Fig. 22. Dorsal view to show venous circulation in vein-net of 

 kidney. The outline of the right nephridium is shown. Centrally the 

 blood channels over liver are drawn, and a portion of the mantle hood 

 is removed to show the ctenidium and its two vessels. The dorsal wall 

 of pericardium is removed to show heart. l 3 / 4 : 1. 



Fig. 23. The gonad. All the alimentary canal, liver and head 

 have been removed. The gonoduct is shown emptying into the forward 

 (sub-anal) portion of the right nephridium. The edge of the muscle 

 separating the sub-anal from the rectal portion of the right nephridium 

 is dotted. Natural size. 



Fig. 24. The pericardium and heart. All the dorsal wall of the 

 pericardium has been removed, and most of that of the ventricle. The 



