130 Records of t/ie Indian Museum. [Vol. XIY, 



perij)ht'riam subangulato, marginc columellari calloso ; dilatato I'uscu, nigromarginato, 

 processuni semilunarem, umbilicum omnino occludeatom emittente. 

 Alt. 30, lat. max. 24, alt. apert. obi. 18, diam. 14-15 mm." 



The teeth, figured on plate XVIII, fig. 6, are almost black. 



The species is a fairly constant one, exhibiting considerable individual 

 variation in shell-colour in respect to the presence or absence of dark 

 spiral bands, but not in sculpture or, except sexually, in form of shell. 

 The shell figured by Kobelt is that of a female ; those figured on pi. XV 

 of this paper belong to both sexes. The species seems to be closely 

 related to T. lacustris, but the shell is larger, thinner and less produced 

 and its sculpture more regular. 



T. shanensis lives in great abundance in the marginal zone of the 

 Inle Lake, especially towards the shore, where the formation of float- 

 ing islands and of peat is proceeding with the greatest vigour. The 

 food consists largely of a somewhat massive alga of the family 

 Rivulariaceae that contains a considerable proportion of calcareous 

 matter. It is perhaps in correlation with this fact that the radular 

 teeth are thicker and darker than those of the other species examined. 



Taia cylindrica, sp. nov. 

 Plate XV, fig. 9 ; plate xvii, fig. 2. 



The shell is thick, of large size, elongate, with the first five whorls 

 sharply conical, and the two basal whorls subcylindrical, there being 

 7 whorls in all. The basal whorl is remarkably oblique. The first 

 four whorls form a regular, moderately broad cone. The fifth whorl 

 is considerably broader than the fourth, but its outlines are hardly 

 convex. It is nearly as long on the dorsal surface as the third and 

 fourth whorls together. The sixth whorl is again considerably broader 

 than the fifth, and about twice as long ; its outlines are a little more 

 convex. In dorsal view the body-whorl is not much broader than 

 the sixth, but more than twice as long. This is owing largely to the 

 abrupt change in the spiral of the suture. In the first four whorls, 

 which may be taken to represent the protoconch, the suture is 

 very regular and not at all impressed ; the fifth whorl is, however, 

 shouldered. Above the sixth whorl the suture becomes impressed, 

 and the upper surface of the whorl is sub-angular. Above the seventh 

 it is also impressed, but considerably more so on the outer part of the 

 shell than on the inner part of the ventral surface. The body- whorl is 

 not shouldered above, and is no broader above than the sixth whorl. 

 The ventral surface of the sixth whorl is considerably swollen. The 

 aperture is broadly ovoid, hardly angulate posteriorly, broadly rounded 

 anteriorly and very oblique both transversely and in its longitudinal 

 plane. The outer lip is slightly produced outwards and downwards. 

 The callus is broad, not so prominent as in some species, irregularly 

 grooved longitudinally. 



The first five whorls are almost smooth to the naked eye, but bear 

 numerous longitudinal and spiral microscopic striae. On the fifth whorl 

 traces of a double ridge can be detected in well-preserved specimens. 

 The sixth whorl bears four spiral ridges, one of which is situated at 



