102 MR. H. F. BLANFORD'S REVIEW OF 
PALUDOMUS CHILINOIDES, Reeve. (Pl. XXVII. figs. 4 a-f.) 
P. constrictus, Reeve; P. phasianinus, Layard (not Reeve); P. levis, Layard; P. (Rivulina) Zeylanica, 
Lea; P. fulguratus, Dohrn ; P. nasutus, Dohrn. 
Shell thick, ovate or ovate-conic, smooth (rarely having traces of spiral sulci on the 
upper part of the whorls). Colour of epidermis citrine or citrine yellow. Shell orna- 
mented with spiral bands of brown crow's-feet markings, which sometimes coalesce into 
transverse zigzags (P. fulguratus), sometimes, but very rarely, into longitudinal (spiral) 
bands. Spire always exserted, sometimes elevated. Whorls 5, all rounded, obliquely 
flattened above; upper whorls more or less eroded; last whorl ventricose. Sutures 
impressed. Aperture ovate, flattened on the columellar side, angulate above. Outer lip 
sharp: inner lip callous, usually white, rarely citrine-tinted on the edge. Interior of 
aperture lined with white callus in old shells. Operculum with small spiral nucleus, 
about central on the longitudinal axis, at about 4rd of the transverse axis from the 
sinistral margin. 
In the above description I have briefly indicated the chief points in which P. chili- 
noides is variable. The most striking of these are the elevation of the spire and the 
markings of the shell; but the differences observable in the latter are not so great as to 
. lead to any doubt of the specific identity of the specimens in question. To illustrate the 
variation of form I give a selected series, Pl. XXVII. figs. 4 a-f, of which fig. 4 « is from 
an unknown locality in Ceylon, figs. 4 and 4c from Peradinia near Kandy, and the 
remainder from a stream at Ballepane, on the Colombo and Kandy road. From these it 
will be seen that, as in the case of Tanalia aculeata, specimens from the same locality 
vary somewhat in form, but in order to ascertain the full extent of variation a wider 
selection is necessary. This series also exhibits a certain amount of variation in point of 
size, but not to the full extent actually observed. I have not, indeed, met with any 
much larger specimens, but smaller shells than fig. 4 « are oceasionally to be met with, 
though rare. 
I distinguish this species from 2. Tanjoriensis chiefly by the smoothness of the upper 
whorls, and by the inferior height and the obtuseness of the spire, which is generally 
eroded. The whorls in all varieties of P. chilinoides are smooth; and though sometimes 
subangulate, owing to the flattening of the upper surface, they never have anything like 
the sharp keel which distinguishes the apical whorls of most varieties of P. Tanjoriensis. 
Moreover, P. chilinoides never exhibits that distinct margination of the sutures which is 
almost invariable in the other species. I have never noticed more than five whorls in 
P. chilinoides, while P. Tanjoriensis has sometimes as many as eight. Varieties occur 
upon which it is difficult to pronounce satisfactorily, but the great majority of the speci- 
mens are so well marked that I have little or no doubt of their specific distinctness. 
: The range of P. chilinoides appears to be confined to the southern provinces of the 
island—at least I have met with no speeimens among the shells received from the 
northern plains. This species is found in streams of all sizes, generally on sand and mud, 
an - frequent in small sluggish brooks as well as in those of more rapid flow. 
The animal is of a dark slate-colour, nearly black on the sides of the foot, muzzle, and 
