THE CINGALESE SPECIES OF PHILOPOTAMIS AND PALUDOMUS. 173 



tentacles. The foot is lyre-shaped, broadest in front, with a round anterior margin, and 

 very obtuse behind. In creeping, the muzzle, which is slightly notched, is pushed in 

 front of the foot, the extremity only and the tentacles being protruded beyond the shell. 

 The eyes are small, and placed externally at the base of the tentacles. The dorsal fold of 

 the mantle is ornamented with a fringe of black filaments. 



PALTJDOMTJS TANJORIENSIS, Gmelin, sp. (PL XXVII. figs. 2 a-e.) 



P. acutus, Reeve; P. (Rivulina) modicella, Lea; P. spiralis, Reeve; P. spurcus, Souleyet; P. lutosus, 

 Souleyet ; P. parvus, Dohrn ; P. palustris, Layard ; P. obesus, Layard. 



Shell elevately conical, smooth with obsolete sulci on the lower whorls, grooved and 

 generally carinated on the upper whorls, which are perfect or but slightly eroded. 

 Epidermis citrine. Shell colourless, or marked with spiral rows of brown dots, which 

 sometimes on the lower whorls, and nearly always on the upper, coalesce into irregular 

 transverse bands of colour. Spire variable in height, sometimes concave, acute, con- 

 sisting of seven or eight whorls when perfect, of which two or three are sometimes 

 eroded. Sutures deep, those of the last whorl, or whorls, marginate. Upper whorls 

 angular : last whorl ventricose, flattened above towards the mouth, usually marked with 

 two to five linear sulci on the periphery. Aperture gibbous ovate, pointed above. Peri- 

 stome white, continuous : outer lip sharp, even : columella callous. 



Like most of the Paludomi, P. Tanjoriensis varies considerably in the elevation of the 

 spire, as is shown by the series of specimens (all from Ceylon) figured. Another series 

 from a small stream near Tindevanum in S. Arcot exhibit almost as great a range of 

 variation, although all collected within the space of a few yards. The development of 

 the spiral grooving of the upper whorls is very different in different specimens, and only 

 the first two or three whorls are distinctly carinated. These characters, however, 

 together with the acuteness of the spire, the deep sutures, and the dotted typical marking, 

 well characterize the species, and distinguish it from P. chilinoides. 



The range of P. Tanjoriensis is very wide. It commences on the northern limit of 

 that of P. chilinoides at some miles from the hills, and ranges over the low country of 

 Northern Ceylon. It is common in the plains of the Carnatic, and I have found it in 

 the neighbourhood of Madras in paddy-fields, and in irrigation-channels at Poonamallee. 

 It is not yet recorded from the northern part of the Madras Presidency, but is found in 

 Central India and Bombay (P. obesus, P. parvus). The P. lutosus of Souleyet, which, 

 as I am informed by Mr. Benson, was taken in the Hoogly, is absolutely undistinguish- 

 able from the typical form ; and in Mr. Cuming's collection are some specimens of the 

 same form, the history of which I do not know, but which are labelled as from Cashmere. 



Of all the species with which I am acquainted, P. Tanjoriensis most resembles such 

 Melanias as M. fasciolata, Oliv., in habit, and it is essentially a species of the plains. It 

 is common on the sandy beds of rivers and in small perennial streams, and I have 

 above noticed its occurrence in the irrigation-channels of paddy-fields. I have also 

 received from Major Skinner specimens from a tank in Northern Ceylon. To this 

 peculiarity of habit it is probably owing that its range is so much wider than that of 



VOL. xxiv. 2 A 



