ig2i.] Manipur Molluscs. 593 



and habits of the species it seems best not to propose taxonomic 

 names for the <3;roups, but they mav be disting;uished as follows : — 



I. Amphibious Group. — Species that liv-e at the edge of 

 marshes and lakes and are amphibious in habits. The dorsal wall 

 of the lung is opaque. The radula is comparatively narrow and 

 the number of longitudinal rows of marginals n^ver exceeds 40. 

 The prostate does not show a spiral torsion and the vas deferens 

 is always long and turns up at the end to open at the tip of the 

 penis. The penis possesses a single retractor muscle. There is a 

 vagina and ^le male and the female ducts open in a common 

 atrium. This group is known to include the following Indian spe- 

 cies, S. indica, S. ckgantior and 5. rntilans. 



II. Terrestriai, Group. — Species found living on the leaves 

 of trees and bushes, at any rate in rainy weather. The dorsal 

 wall of the lung is thin and translucent. The radula is broad 

 and has over So longitudinal rows of marginal teeth. The vas 

 deferens is rather short and straight. The penis is small and 

 without a retractor muscle. The prostate has a spiral torsion. 

 There is no distinct vagina or atrium, but the ducts of the recep- 

 taculum semiuis, the penis and the vagina open separately in a 

 shallow slit-like common aperture on the surface of the body. 

 The only Indian species of tliis group so far known anatomically is 

 S. seniiserica. 



Of the anatomy of most species of Snccinea very little is 

 known and practically no work has been done on the Indian species. 

 Von Rieper' has given a full description of the genitalia and 

 physiology of 5. putris, while Ihering* gives a general account of 

 the genitalia of the same species. J acobi in his paper on Japanese 

 Pulmonates' also gives a few notes on the anatomy of S horticola . 

 Reinh. Both of these Palaearctic forms belong essentially, at any 

 rate as regards the radula and the generative apparatus, to my 

 Amphibious Group. The small number of marginals, the presence 

 of a retractor muscle and the large thick penis-sac are very alike, 

 but Jacob! in his figure shows the different sexual ducts as having 

 separate external openings. 



At first it was intended to describe only the anatomy of 5. ele- 

 i^antior, but as many interesting points came out in the dissection 

 of other species it was decided to include short notes about them 

 also for comparison and further reference. 



Succinea elegantior, Annandale, sp. nov. 



A species resembling 5. seniiserica, Gould, externally but with 

 the shell smaller and narrower and having the spire still further 

 reduced. 



The shell is rather small, thin but less fragile than in some 

 species, of narrowly ovate form, of a bright golden browu 



' Ann. Soc Roy. Malac. Belgiqiie X\.\'\\, pp. 125-191 (1912). 

 ' Jahrh. De-;t. Malakozool.Ges. IV, pp. 136-142 (1S77). 

 ' Jourii. Coll. Sci. Tokyo XXI, pp. S2-S5 (iSgS-iqooj. 



