574 Records of the Indian Museum. [Vol. XXII, 



with the outer and inner cusps larger than the others. Their 

 bodies are long, narrow and oblique. 



The oesophagus is long and narrow, the gizzard large and 

 powerfully developed, occupying the greater part of the stomach. 

 The genitalia do not differ material!}' from those of other Indian 

 species. The penis-sheath is large and sausage-shaped, pigmented 

 and of a greyish colour. The spermatheca, which is full of sperma- 

 tozoa in specimens examined, is pyriform and possesses a duct 

 about half as long as itself. 



Type-specimens. — M 11717/2, Zool. Surv. Ind. [hid. Mas.). 



Locality, etc. — This species was found in fair abundance in a 

 drying peat-swamp on the east side of the L,oktak Lake, Manipur, 

 in February, 1920. It leads an almost amphibious existence in 

 and on the damp mud at the edge of bufialo-wallows and other 

 small pools. There is no true aquatic vegetation in its haunts and 

 it appears to feed on mud and decaying vegetable matter. A 

 specimen was found to be heavil}' parasitized with sporocysts and 

 cercariae, but unfortunately all those brought living to Calcutta 

 for examination died on the waj'. Specimens were also obtained 

 in a pool of very foul water in the jungle near Dimapur, Assam. 



There can be little doubt about the affinities of L. ovaJior, 

 which is evidently no more than a final link in the chain of evolu- 

 tion of which L. andersoniana with its diverse phases is the predom- 

 inant component. We will discuss this point further when deal- 

 ing with that species. 



Limnaea andersoniana, Nevill. 

 (PI. VIII, figs. 1—6.) 



1908. Limnaea (Giiluan'a) simu/ans, Preston, Rec. hid. Mas. II, p. 49, 



fig. 6. 

 1918. Limnaea andersoniana. Annandale, /Pet-. Iiid.Mifs. XI\ . pp. loO, 



149. figs. 4a, 46. 



In his original description of L. andersoniana, as one of us 

 has pointed out in the paper cited, Nevill included, in addition to 

 the central Asiatic form he later recognized as distinct, two that at 

 first sight appear rather different. The view that these represent 

 respectively a pond and a stream phase of a single species is fully 

 borne out by recent observations in Manipur and eastern Assam, 

 in which L. andersoniana is abundant. Further particulars may, 

 therefore, now be given. 



The forma typica of the species, as represented by Nevill's 

 type-specimen (pi. VIII, fig. i) from Nantin in Yunnan, has a 

 small, rather fragile shell of a pale brownish colour and an ovoid 

 form. The spire is acuminate and exserted, but by no means long. 

 There are 4^ whorls and the spiral is moderately oblique. The 

 suture is impressed and the upper extremity of each whorl is 

 narrowly flattened outside it. The lowest whorl of the spire is 

 much narrower than the body-whorl and is situated on its inner 



