88 SUCCINEIDJE. 



Animal limaciform, blunt before, short behind ; tentacles 

 simple ; mantle large, central, its margins holding the edges of 

 the external shell ; no longitudinal furrows above the margin of 

 the foot, and no caudal mucous pore ; no distinct locomotive 

 disk ; external respiratory and anal orifices on the right central 

 margin of the mantle ; generative orifice below and behind the 

 right ej^e-peduncle. 



Shell external, its margins embedded in the mantle, rudi- 

 mentary, paucispiral, oval, depressed, unguiform. 



Jaw smooth, with median and accessory quadrate plate. Lin- 

 gual membrane with tricuspid centrals, tricuspid laterals, and 

 multifid quadrate marginals. 



Hyalimax, H. and A. Ad., 1855. 



JDistr. — Mauritius, Nicobar Islands. H. pdlucidus, Quoy 

 (ci, 49, 50). 



Animal limaciform, swollen at centre, blunt before, and 

 tapering behind ; tentacles simple ; mantle large, central, con- 

 cealing all but a small opening ; an internal shell-plate ; no longi- 

 tudinal furrows above the margin of the foot, and no caudal 

 mucous pore ; no distinct locomotive disk ; external respiratory 

 and anal orifices on the central right margin of the mantle ; 

 orifice of combined genital system on right side of head, half- 

 way between eye-peduncle and mantle. 



Shell large, vudimeniary, thin, oval, unguiform, non-spiral. 



Jaw smooth with blunt median projection and accessory 

 quadrate plate. 



Lingual membrane with tricuspid central teeth, multifid 

 laterals, and quadrate marginals. 



LiTHOTis, Blanford, 1863. 



JHdr. — 3 sp. India, Tahiti. L. riqncola, Bl. (c, 40). 



Shell external, auricular, ovate, thin, with an external longitu- 

 dinal carina and corresponding internal sulcus ; aperture rather 

 large, continuous ; spire small. The animal has large eyes, on 

 short, retractile peduncles tumid towards- the base ; inferior 

 tentacles not visible ; foot short, pyriform. 



Jaw oxygnathous ; radula like Helix. 



The position of this genus is uncertain; it appeals to agree 

 with the Succineidae in the want of inferior tentacles, but differs 

 in the character of the jaw. 



Catinella, Pease, 18*n. 

 Distr. — 3 sp.. Polynesia. G. rubida, Pease. C. explanata^ 

 Gld. (c, 34). 



Shell planulate, fragile, spire rudimentar3\ Arboreal. 



