THE CINGALESE SPECIES OF PHILOPOTAMIS AND 711. 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 XXVIT. 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 REGALIS, 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 
thosein 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, 4 towards the front. The callus 
continuous to the junction of the outer lip. Opereulum obliquely pyriform, obsoletely 
Spiral, subconcentric : nucleus rather variable in position near the dextral margin, and 
from 1th to 2ths 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 4 moderate series from Kandy, Ambegammoa, and the Baleadua Pass is sufficient, 
I think, to convince any one that they are specifically identical. In some small specimens 
