548 Records of the Indian Miiseitiii. [Vox,. XXII, 



The radula has the denticulations of the teeth rather numer- 

 ous and coarse but otherwise offers no particular feature of interest. 



The animal offers no noteworthy particular except that it is 

 rather pale in colour. The edge of the mantle is thin and almoet 

 smooth in the adult, at any rate in preserved specimens. 



Tvpe-serics. — No. M 1 1836/2 Zool. Surv. Ind. (Ind. Miis.). 



Distribution. — This species is only known from Dimapur, 

 which lies in the plains of Assam immediately north of the Naga 

 Hills and about 100 miles north of the Manipur valley. Nevill 

 examined specimens from Assam but of unknown provenance. 



Affinities. — I do not think that this species has anj- close rela- 

 tionship to the thick-shelled Indo-chinese forms with which Nevill 

 associated it under the name Paludina bengalensis var. (or subsp.) 

 cingulata. The shells he examined were old and in them the very 

 characteristic sculpture and colouration was obscured. The em- 

 bryonic shell is so unlike that of V . bengalensis and so like that of 

 V. oxytropis that I believe V. microchactophora to be related rather 

 to the latter species. 



Habits. — The species was found in artificial ponds, particularly 

 on floating grass-stems and the lower parts of plants that trail 

 on the surface of water. In a rather deep clean pond, with a 

 bottom of stiff yellowish clay and a rather profuse growth of 

 Hydrilla, reserved for the water-supply of the Manipur Road 

 railway station and the surrounding houses, large numbers died 

 at the beginning of Mar-:h, 1920, and by their decay gave the 

 water a horrible ammoniacal smell. In a shallow, swampy pond a 

 few hundred yards away many individuals were observed alive and 

 active. 



Vivipara oxytropis (Benson). 



(Plate IV, figs. 2-5.) 



1836. Paludina oxytropis, Benson, Journ. As. Soc. Bengal V , p. 745. 

 1852. Paludina pyramidata, Kiister, Martini and ("homnifz's Conch. 



Cab., pp. 27, 28, pi. vi, figs. I. 2. 

 1864. Paludina o.xytropis, Reeve, Condi. Icon., pi. ii, fig. 9 

 1909. Vivipara o.xytropis, Kobelt, Martini and Chemnitz's Condi. Cab.. 



p. 132, pi. XXIV, figs. 9, 10. 

 iqis. Vivipara o.\vtropis, Preston. Faun. Brit. Ind. Fresliw.-Moll., p. 



84. 



The shell is large or ver^' large but thin and delicate, rather 

 broadly conical, acuminate, narrowly perforate, ornamented with 

 prominent spiral ridges, highly polished and of a bright trans- 

 lucent olive-green when clean and fresh. The base is flattened 

 and recedes abruptly below the peripheral ridge of the body- whorl, 

 especially on the ventral surface. There are si whorls, but the 

 terminal half whorl is minute. The other whorls of the spire 

 increase in size gtadualh'. The suture is very little impressed and 

 all the whorls are broadly but a little obliquely flattened outside 

 it. The body-whorl as seen in dorsal view is transverse, l3Ut 

 widens abruptly towards the aperture. It is broadly but obliquely 

 flattened above and not at all tumid. The aperture is subcircular or 



