MOLLtrSCA OF INDIA. 25 



CTCLOSTOMACEA. 



Graj- writes in the ' Catalogue of the Phaneropneumona,' p. 2 : — 

 " In Ci/clostoma, which have a shelly operculum and simple mouth 

 to the shell, the foot of the animal is divided into two equal parts 

 b}' a longitudinal groove, and the animal walks by alternately 

 moving forward first one and then the other of these sides. In 

 Cyclophorus, Pteroci/chs, and Megalomastoma, which have a horny 

 many-whorled operculum, the foot is simple and the animal glides 

 along like other Gasteropodes. Some of these, as Pteroci/clos, have a 

 more or less developed groove or hole at the hinder angle of the 

 mouth. In others, as Megalomastoma, there is a prominent 

 appendage to the mantle, which produces a groove and ridge 

 in front of the mouth near the pillar, and in Fajjina, which has 

 been confounded with Buccina, the groove ends in a narrow-edged 

 marginal notch." 



This permanent appendage to the mantle referred to I have not 

 yet seen, nor do I know whether Gray or some other naturalist has 

 described it in proper detail. 



Family CYCLOSTOMID^. 



Cydophoridce, Gray, Nomencl. of Moll. Anim. & Shells Coll. Brit. 

 Mus. 1850. 



Genus Otopoma, Gray. (Plate LXVII.) 



Otopoma, Gray, Cat. Cycl. p. 35. 1st type, foliacemn, Chemnitz ; 

 2nd type, Ci/clostoma datisum. Sow., Arabia. The majority of the 

 other species placed in the genus have the umbilicus quite exposed. 



Otopoma, Pfeiflfer, in Z. f. M. p. 157 (1851); Consp. p. 29; 

 Pneum. Mon. p. 179 (1852). 



Divided into 2 sections (Cat. Phanerop. B. M. 1852): — 



Group A. Umbilicus perfectly closed. Type Cyclostoma 

 clausum : Arabia. 



Group B. Umbilicus more or less open. 



Section 1. Eight margin of the peristome expanded. 

 Includes : — 



C. auriculare, Gray. — ? 



C. albicans. Sow. Hainan. 



C. naticoides, Recluz. Socotra. 



C. guillaini. Ex coll. Dohrn. Mogadoxa, 



C. unifasciatvm. Sow. Madagascar, Mauritius. 



