66 CYLINDRELLID-iE. 



Family CYLINDllELLID^. 



Shell cylindrically turriculated, many-whorled, the last vhorl 

 more or less detached at the aperture; apex of the spire usually 

 truncated. 



Jaw thin, formed of oblique plications, angular in the middle; 

 radula narrow, the central tooth very narrow, the laterals leaf-like, 

 oblique, the marginals sometimes resembling the laterals, but 

 smaller, sometimes very short, rudimentary. 



Cyltndrella, Pfeiffer, 1840. 



Distr. — 193 species. Tropical America. 



Shell convex-cylindrical, many-whorled, truncate at the apex ; 

 whorls slowly increasing in size, the later ones frequently con- 

 stricted, the last partly or wholly free, angulated or subcarinated ; 

 aperture subcircular, peristome reflected, continuous. 



The true Cylindrellae are chiefly represented in the islands of 

 the West Indies. They have been distributed, with regard to the 

 radula, in the following manner : — 



Grroup 1. Cylindrella proper ; only two lateral teeth on each 

 side, the following " marginal " teeth of very difl'erent form and 

 in various numbers. C. Trinitaria, Pfr., C. gracilis^ Wood, 

 G. Bahamensi^, Ffr., G. cos^^ia, Gruilding, G. Agnesiana, Adajns, 

 and G. Brooksio.na, Grundlach. This division contains the groups 

 called Casta, Trachelia and Mychostoma by Albers. 



Group 2. Callonia, Crosse and Fischer : more than two lateral 

 teeth, marginal teeth not very diiferent ; median tooth very 

 narrow. G. Elliott, Poey. 



Group 3. Thaumasia, Albers : more than two lateral teeth ; 

 marginal teeth not differing from them. (7. perlata, Gundl., 

 G. Vignalensis, Wright, C.&reois, Pfr., C.scaeua, Gundl., G.rosea^ 

 Pfr., G. sanguinea, Pfr. 



I question the propriety of separating the groups indicated 

 above by slight diflE'erences in dentition ; so few observations 

 have been made, and the characters are also so mutable, that it 

 .appears more natural as well as more convenient to continue to 

 employ the old subgeneric names with diagnoses made up prin- 

 cipall}^ from characters of the shell. 



ANOMA, Albers, 1850. Shell elongated, turriculated, fusiform, 

 subtrnncated, attenuated to the summit ; twelve to eighteen 

 whorls, the last not free or decliuing, carinated at the base; aper- 

 tvire rounded-oblong, expanded in front ; peristome thin, ex- 

 panded. G. tricolor, Pfr. (xcix, 41). 14 sp. Cuba, Jamiaca, 

 Mexico. 



THAUMASIA, Albers, 1850. (TJrocoptis, Beck [pt.], 1831.') Shell 

 rimate, ovately ejdindrical or subventricose ; whorls 8-10, regu- 

 larly increasing, the last scarcely free, obsoletely carinate ; 



