THE CINGALESE SPECIES OF PH1LOPOTAMIS AND PALUDOMUS. 169 



covered with a zigzag marbling, but more frequently this is broken up into inter- 

 rupted spiral bands, and in other specimens, again, the bands are continuous, resembling 

 those which characterize P. bicincta, but narrower and more numerous. The colouring is 

 only visible in the interior, and, in old specimens, is concealed beneath a white callous 

 deposit of the mantle. The edge of the peristome is generally, but not always, tinted 

 with brown. 



The operculum is normally as figured in Plate XXVII. fig. 11, but, as in the case of 

 Tanalia, is not unfrequently destroyed, and replaced by one having a concentric structure. 

 If this takes place at an early age, the nuclear portion of the operculum is alone so 

 formed, the later-formed layers having the usual arrangement. I found that, in a 

 stream at Hautanne, more than half the specimens had lost portions of their opercula, 

 and one or two full-grown shells were totally divested of this appendage. The shells of 

 these specimens were also eroded in holes in a manner difficult to account for. 



PHILOPOTAMIS IIEGALIS, Layard. 



This appears to be a rare shell. I saw no specimens of it in Major Skinner's collec- 

 tion, nor have I met with it myself in Ceylon. The only specimens I have seen were 

 those in Mr. Hugh Cuming's collection, obtained, I believe, by Mr. Thwaites. I am 

 thus unable to add anything to Mr. Layard's description from my own observations ; but 

 I may remark that it appears to differ in no respect from P. sulcata, except in possessing 

 a row of small scale-like spines round the upper edge of the whorl. I cannot but think 

 that it may eventually prove to be a variety of P. sulcata. 



PHILOPOTAMIS GLOBULOSA, Gray. (PL XXVII. figs. 1 a-e, 12 a, b.) 

 P. abbreviata, Reeve; P. bicincta, Reeve; P. clavata, Reeve. 



Shell globose or ovate, solid, smooth, rarely bearing faint traces of spiral sulci. 

 Epidermis yellowish brown. Shell colourless, or ornamented with two or three spiral 

 bands, only visible in the interior of adult shells. Spire depressly conical, variable in 

 height ; apex usually eroded. Whorls flattened, the last more or less elongated, depressly 

 flattened above, produced below. Aperture semi-ovate to obliquely pyriform, subcanali- 

 culate behind, lined interiorly with a callus, sometimes tinted yellow towards the exterior 

 margin. Outer lip sharp. Columella callous, arcuated towards the front. The callus 

 continuous to the junction of the outer lip. Operculum obliquely pyriform, obsoletely 

 spiral, subconcentric : nucleus rather variable in position near the dextral margin, and 

 from ^th to f ths the height of the operculum. 



The shell of this species is always yellowish brown (the colour of the epidermis), and 

 shows less tendency to variation than most of its allies. The chief points of variation 

 observable are the form, which is sometimes globose, sometimes elongate (but exhibit- 

 ing all intermediate gradations) ; and the painting, which is sometimes developed, more 

 frequently not, and in the former case only in the interior of the adult shell. Two 

 extreme] forms have been described as P. globulosa and P. bicincta, but the comparison 

 of even a moderate series from Kandy, Ambegammoa, and the Balcadua Pass is sufficient, 

 I think, to convince any one that they are specifically identical. In some small specimens 



