100 PROCEEDINGS OF THE MALACOLOGICAL SOCIETY. 



last species. Genital nerve having a branch to the posterior end 

 of the diaphragm. 



Jaw broad, 1*9 mm. long (when flattened), thin, nearly- 

 smooth, but crossed by very fine transverse striae in addition to 

 the equally fine lines of growth. Median projection broad and 

 very low. 



Radula measuring about 4" 7 x 2' 2 mm. when flattened 

 out. Central and lateral teeth tricuspid, with shorter mesocones 

 than in the H. gomesianus. Their ectocones are short and quite 

 separate from the mesocones ; the endocones are narrow and 

 poorly developed, being united with the mesocones along the whole 

 length of their inner sides. Marginal teeth very numerous and 

 very close to one another, gradually decreasing in size from the 

 transitional teeth to the edges of the radula. Endocones absent 

 on the marginal teeth ; ectocones almost as long as the mesocones, 

 with which they are united for the greater part of their length. 

 The bifid cusps thus formed are strongly curved, and have their 

 outer edges serrated, this serration becoming more and more 

 pronounced towards the outer limits of the radula, so that, while 

 the inner marginal teeth might be described as bicuspid, the outer 

 marginals would be better described as multicuspid. Bases of 

 marginal teeth narrow, about two-thirds of the length of the cusps ; 

 bases of the other teeth broader, with concave outer edges. Rows 

 of teeth obtusely angled in the centre, whence they trend slightly 

 forwards on each side. The total number of teeth is more than 

 twice as great as in H. gomesianus, the radular formula being : 

 (86 + 14 + 1 + 14 + 86) X 128. In order to compensate for 

 the small size of the outer marginals, a few short additional rows 

 of these teeth are intercalated at the edge of the radula. 



Alimentary Canal. — Buccal mass large, the extremity of the 

 radula-sac projecting from its hind end. (Esophagus rather short, 

 thin-walled, with internal longitudinal folds ; sometimes swollen 

 into a dorsal, backwardly directed pouch at the point where it 

 bends down to pass under the cerebral commissure. Crop large, 

 about 2 mm. in diameter, its front end projecting forwards on 

 the left side. The anterior part of the crop has rather thick walls 

 with internal transverse folds ; the hinder part passes 

 imperceptibly into the large, elongated, thin-walled stomach. 

 This in turn gives rise to the thin- walled intestine, which describes 

 the usual S-shaped curve, before passing forwards as the rectum, 

 in the same manner as in the last species. 



Salivary Glands broad, about 4 mm. long, and united with 

 each other above the crop, a large portion of which they cover, 

 although they do not usually reach quite to its front end. Salivary 

 ducts of the usual form. 



Liver consisting of a posterior division behind the stomach, 

 and a rather extensive anterior division, in which the loops of 



