igiQ-J 



N Ann AND ALE : Bouihav Streams Fauna. 



143 



Length 



Breadth 



Length of aperture 



Breadth of aperture 



15 mm. 

 9 mm. 

 9 mm. 

 6 mm. 



The radula (pL V, fig. 3) is very similar to that of L. acumi- 

 nata, except that the central cusp of the lateral teeth is consider- 

 ably longer, all the cusps of these teeth sharper, and in there 

 being a second internal cusp resulting in four cusps in all ; the 

 fourth cusp is situated at a lower level than the others. The 

 cusps of the marginal teeth are more regular and have a distinctly 

 pectinate appearance. The central tooth is trilobed and distinctly 

 asymmetrical. 



Fig. 4. — Genitalia oi Limnaea clilanivs, Benson, 

 r.ettering as in fig. 3, p. 142. Sp. D.=spermathecal duct. 



The central part of the horny upper jaw is broad, but the 

 outer margin is less convex than in L. acuminata ; its colour is 

 paler than in that species. 



The genitalia (text-fig. 4) of this species differ from those of 

 L. acuminata mainly in the much greater length of the proximal 

 part of the male duct and the hermaphrodite duct ; in the posi- 

 tion of the accessory and the albumen glands, which are situated 

 close to the junction of the male and female systems rather 

 nearer the hermaphrodite gland than the uterus, and in the con- 

 siderable length of the spermathecal duct, which is as long or 

 nearly as long as the spermatheca. The penis-sheath is also 

 thicker. 



