:;_' 1 CHOKisTii>.i-:-nM u.<x;Yi:ii>.r.. 



(acuhir process-si a papilla on either >i<l between tin- mantle and 

 font, and two posterior threads In-low the operculum. Jaws elliptic. 

 Kadula with three raehial teeth, of which the middle is very small, 

 the Miliers imieuspid, lateral tooth lar-v. hieuspid, marginal small, 

 curved, simple, a small hasal plate exterior to them ( IM. ~>4, fig. 5). 



Genus CHOR 1ST MS. Carpenter. 1*7:.'. 



The characters are those of the family, the systematic position of 

 which is very uncertain. Verrill is inclined to place it among the 

 teetihranchs, near Action, but the shell and appendages of the 

 epipodilim recall Rissoid characteristics. 



C. ELEGANS, Carp., described from Canadian post-pliocene fossils, 

 has heen found living on the Now England coast, within the egg 

 capsule of a ray. 



FAMILY HOMALOGYRID^E. 



Body flattened, ciliated in front, no tentacles, eyes sessile (PL 

 '-I. iig. 3). Radula narrow, the central tooth having a quadrangu- 

 lar base with large cusp, imbricated, one series on the other, a 

 lateral, transverse plate replaces the lateral and marginal teeth. 



(PL 54, fig- 40 



Shell planorbiform, spire involute, mouth clasping both sides of 

 the periphery. Operculum corneous, few-whorled, nucleus central. 



Genus HOMALOGYRA, Jeffreys. 1867. 



Characters those of the family. H. NITIDISSIMA, Forbes & 

 Hanley. Europe, Greenland. 



The external characters of the animal and its dentition are pe- 

 culiar, and its systematic position is uncertain. 



Omalogyra, Jeffreys, and Ammonicerina, Costa, are synonyms. 



