EASTERN PROVINCE SOUTHERN REGION SPECIES. 411 



remarkable differences in Ibe form of tlie axis, often furnished with re- 

 volving lamin;TB or other curious processes ; aperture subcircular, eden- 

 tulate ; peristome expanded, continuous. 



A West Indian genus, represented only in the Florida Subregion 

 within our limits. 



Jaw as in Maeroceramus, described below. 



The dentition of the genus is very lioculiar and constant in the various 

 groups or subgenera. The lingual membrane is exceedingly long and 

 inirrow. The base of attachment of the centrals is small, long, narrow, 

 with the upper margin broadly retiected into a blunt, rounded, and 

 expanded, gouge shaped cutting i)oint; the laterals have a long, sub- 

 quadrangular base of attachment, bearing below a large, bluntly 

 rounded, greatly expanded, palmate cusp and cutting point, represent- 

 ing the inner and central cusps of the laterals, and above a long, 

 slender, graceful extension, representing the external cusp of the other 

 EeUcidce, This last is bluntly truncated or bears a recurved cusp, 

 smaller but of same shape as that below, or it has a laterally extended, 

 small, blunt point. la some species the laterals extend to the margin 

 of the lingual membrane ; in others there are distinct marginal teeth, 

 long, narrow, laminar, with bluntly recurved apices. A full descrip- 

 tion and figures of these various forms of teeth will be found in Journal 

 de Conchyliologie, January, 1870. 



Subgenus GOis^GYLOSTOMA, Albers. 



Animal small and short compared with the shell, in general like that 

 of PaUda ; eye-peduncles of medium length, the tentacles quite short. 

 Motions sluggish ; the shell drags horizontally, nearly in the line of 

 motion. 



Shell cylindrically- fusiform or conic-turreted, apex attenuated, cos- 

 tellately striate ; whorls 9-20, the last more or less protracted, terete, 

 sometimes obsoletely angulated ; aperture circular; peristome expanded 

 in every part. 



The lingual membrane of three species only is known— C. elegans, 

 C. ornata, and C. Foeyana. They all agree in their 

 characters. On the laterals the inner cutting pal- 

 mate cusp (it can hardly be called a cutting edge or 

 point) is surmounted by a simple, long, squarely <^- 

 truncated extension ; the outer palmate cusp is on a 

 long pedicle ; the change from lateral to marginal 

 teeth is very gradual; the last become very small, ^'"^VplJ^aHa? 



Liujiual (leutitioil of 



