1881.] Mollusea of the Indo-Malayan Fauna. 163 



keelless form specifically. If the latter be united, it would perhaps lead 

 too far ; the umbilicus is sometimes so much covered that G larclayanum 

 could scarcely be separated. Even G. ligatum, as hinted by M. Morelet, 

 would become questionably distinct. G. erroneum is to be found abundant- 

 ly, subfossil only, in the coralline sands, near the seashore, on the West 

 Coast of Mauritius. My friend Mr. J. Caldwell possesses a very numerous 

 and fine series. 



var. subunicolor, nov.' 



A variety which instead of being subangulate at the periphery is 

 distinctly keeled ; two or three of the spiral striae between the keel and the 

 suture are also slightly more prominent than the others, showing a distinct 

 tendency to C. carinatum and its variety: the base is, however, persistently 

 and regularly sulcated as in my type form ; this is doubtless the var. B. of 

 Morelet. 



Alt. 23, diam. 24i mil. 



var. stjbocclttsa, nov. 



The columellar margin broadly reflected, almost covering the umbili- 

 cus ; spiral striation more acutely raised than usual ; scarcely keeled at the 

 periphery. 



Alt. 23i, diam. 24 mil. 



var. subligatum, nov. 

 Banded below the subangulate periphery ; a small form with very fine 

 spiral striation, which is also less developed at base. 

 Alt. 16|, diam. 18| mil. 



Omphalotropis dupontiana, G. Nevill, PI. VI, Fig. 8. 

 Handlist I, 1878, p. 320, Pouce Mn., Mauritius. 



Openly and deeply umbilicate, rather solid, colourless and without 

 sculpture, at least in its present subfossil state, ovately conical; spire con- 

 vexly conical, very acute, with the suture somewhat excavate ; whorls 6, 

 convex, short, increasing slowly and regularly, the last one ventricose, 

 remarkable by its shortness (it appears almost round), the base not being 

 produced as is the case almost universally, rounded at the periphery with 

 a very acute and well defined keel boldly and most characteristically encircling 

 the very open umbilicus ; aperture ovate, rather contracted above and 

 dilated below, the margin not continuous, peristome scarcely thickened, 

 regularly rounded, columellar margin lightly reflected, oblique, distinctly 

 subangulate below, the basal margin is again indistinctly subangulate where 

 the keel terminates. 



Long. 6, diam. 4s mil. 



