Tornatellidse, and Pyramidellidae. 455 



usually the case with all the smaller and shorter Chemnitzia. We 

 have frequently taken it in small pools at Exmouth, in the lit- 

 toral zone, in company with C rissoides. 



In this species I see no departure from the generic charac- 

 ters of the tribe to invalidate its reception as one of the Chem- 

 nitzia; there are only the specialties of individual animals. The 

 reflexion of the apical turn alone would almost have determined 

 me to allocate this species in Chemnitzia, but the examination 

 of the soft parts afforded such decisive proofs of its identity 

 with that genus, as to leave no alternative. A new genus and 

 specific appellation have lately been assigned to this object, which 

 I really think may be dispensed with ; I cannot see the utility 

 of forming new genera to receive species which have already 

 provided for them suitable and characteristic generic receptacles. 

 This practice only adds useless matter to our already overbur- 

 thened annals. The present species has enjoyed two specific 

 names within a few years, but as it is ascertained to be the 

 Rissoa ? diaphana of Alder, it will only be an act of justice to 

 that excellent malacologist to revert to his original appellation. 

 If this arrangement is acquiesced in, the O. diaphana of Mr. Jef- 

 freys in the^' Annals,^ voL ii. S. 2. p. 330 (No. 11), quite a differ- 

 ent species, will require, as a Chemnitzia, a new specific name. 



Chemnitzia rissoides. 



Odostotnia rissoides, nonnuU. 



Animal inhabiting a spiral pale horn-colour shell of four and a 

 half rather tumid volutions stamped with very fine lines of in- 

 crement. Mantle not produced beyond the margin of the shell. 

 Head short, flat, not grooved or cloven, gently arcuated at its 

 termination ; it issues between the foot, and in this species a ten- 

 tacular veil, which, mth the tentacula, extends a little beyond 

 the foot ; the veil is entire with a sweeping indentation which 

 resolves itself at the right and left angles into two very short, 

 broad, awl-shaped, bevelled, blunt tentacula, on which there is 

 an opake linear stripe from base to point ; they are hyaline, seta- 

 ceous, with the tips marked with a round opake white dot, which 

 in certain aspects give them a clavate appearance, and at the 

 under part they are aspersed with minute sulphur points ; the 

 eyes are large, very black, imbedded in the skin a little below 

 the origin of the tentacula at their internal bases. The foot is 

 very short, strictly truncate in front, scarcely auricled, with a 

 vei*y rounded posterior termination at half extension, but on the 

 mai'ch tapers to a lanceolate point ; it carries at a little distance 

 from the terminus of the pedal disk, on a simple operculigerous 

 lobe, a slightly arcuated, suboval, light horn-coloured operculum. 



