1869.] Contributions to Indian Malacology. 129 



culum fusco-corneum, per-simile Mi Cyclophori planorbis, marginibus 

 externis anfractuum laciniatim productis. 



Diam. maj. 6 J, min. 5J, axis 3J millem. ap. diam. intus 2 J. 



Sab. Gum C. planorbo in montibus Calcacl Hills dictis. 



Shell openly umbilicated, depressly convex, thin, smooth, shining, 

 glassy, of an olive colour, with minute sub-obsolete decussating stria?, 

 only visible beneath a powerful lens. Spire convex, apex obtuse, 

 suture impressed and with an internal margination, due to the pro- 

 longation on the inner whorls of the keel surrounding the shell. 

 Whorls 4, convex ; the last descending slightly near the aperture, and 

 becoming paler in colour in front on the outer half of the surface 

 only, so that a band of darker colour surrounds the shell close to the 

 suture. Of the two keels one is at the periphery, and rather lower 

 in position than usual, owing partly to the raised spire, the other is 

 at the base, rather towards the umbilicus, which exhibits all the 

 whorls, and is closely spirally ribbed inside. Aperture round, oblique, 

 peristome in one plane, simple, thickened. Operculum very similar 

 to that of Cyclophorus planorbis, with the external edges of the whorls 

 lengthened, ragged and split up into a fringe-like edge. Major dia- 

 meter 0.26, minor 0.22, axis 0.14 inch. 



This very beautiful little species has much more of the character of 

 C. (Ditropis) planorbis than of G. Beddomei, having the same glassy 

 structure and high lustre. The convex form is peculiar and very 

 unusual amongst the Gyclophoridce. 



The next two species are at least equally peculiar with the last 

 three, and I was for some time much puzzled as to their position 

 amongst the Cycloplioridce, until more close examination of the oper- 

 culum, revealed its peculiar structure and its resemblance to that of 

 Opisthoporus. Mr. Benson, some years ago, proposed that should other 

 species be found, resembling Opisthoporus in the characters of the 

 operculum, but wanting the sutural tube, they should be classed with 

 the typical forms under the name Ccelopoma* This remark, how- 

 ever, was especially intended to apply to Gyclotus variegatus and its 

 allies, with which the types of Opisthoporus had been classed by 

 Dr. Pfeiffer. In point of fact, the sutural tube of Opisthoporus is 

 * Ann. and Mag Nat. Hist, for 1855, Ser. 2, Vol. XV. p. 15. 



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