1921.] Manipur Molluscs. 599 



The male portion of the genital system is somewhat different. 

 The prostate is sub-circular and the vas deferens moderately thick. 

 The penis is elongate and has a recurved tip, which is in continuity 

 with the vas deferens. The retractor muscle is attached at the 

 point of curvature. 



In the female organs the uterus is much coiled on itself and 

 becomes considerably narrowed at the point where the duct of the 

 receptaculum seminis joins it. The duct of the receptaculum 

 seminis is long and narrow. The vagina is elongate and thick. 

 The male and the female ducts open in a common vestibulum, 

 which is quite short. 



The jaw is slender and has blunt ends. Its cutting margin is 

 without any irregularities, smooth and evenly concave. The quad- 

 rate accessory plate is as broad as the 

 jaw itself and rounded posteriorly. 



The radula is a long narrow rib- 

 bon with only about 35 teeth in a 

 transverse row. The dental formula is 

 6. II. I. II. 6. The teeth are normal as 

 regards shape and structure : it is the 

 small number of marginals that is ,. . , c c ■ *■ 



noteworthy. In the smgle available ' /a„s, Bl.-mford. 



radula a very interesting abnormality 



was noted "in that the seventh lateral tooth on the right side 

 throughout the length of the ribbon has assumed to all appear- 

 ances the form of a central tooth. 



Succinea semiserica, Gould. 



This species has a fairly wide distribution. It has been found 

 in Eastern Bengal, at Calcutta, in Pegu in Burma and in the 

 Amherst and Tavoy districts of Tennasserim. Dr. H. H. Marshall 

 of Rangoon, who has kindly sent the preserved specimens on which 

 this study is based, has supplied the following information about 

 its habits and environment: — 



"This species is very common during the rains round Ran 

 goon in the islands in Hlewa-ga Lake and in Mr. Taylor's Islanc 

 in the Kokim Lake. They are generally found living on thi 

 leaves of various plants, bushes and in moss-grown localities 

 They seem to prefer mangoe, plantain and palm leaves." 



From the above statement it will be seen that the animai 

 lives mainly on fresh leaves and does not frequent dirty marshy 

 places like those of the other group, which seem to prefer decay- 

 ing vegetable matter as food. This species was found, moreover, 

 in the rainy season, from June to September, while those of the 

 other group have been commonly met with during the months of 

 December to March. 



The animals I have examined are very much contracted and 

 probably bleached owing to preservation in strong spirit. The 

 body is bulky and the foot is narrowly tongue- shaped. The ven- 



