66 CYLINDRELLIDA. 
Famity CYLINDRELLID A. 
Shell cylindrically turriculated, many-whorled, the last whorl 
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. 
CYLINDRELLA, 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 Cy lindrelle are chiefly represented in the islands of 
the West Indies. They have been distributed, with regard to the 
radula, in the following manner :— 
Group 1. Cylindrella proper; only two lateral teeth on each 
side, the following ‘ marginal” teeth of very different form and 
in various numbers. C. Trinitaria, Pfr., C. gracilis, Wood, 
C. Bahamensis, Pfr., C. costata, Guilding, C. Agnesiana, Adams, 
and C. Brooksiana, Gundlach. 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 different; median tooth very 
narrow. C. Ellioti 7 eoey: 
Group 3. Thaumasia. Albers: more than two lateral teeth ; 
marginal teeth not differing from them. C. perlata, Gundl., 
C. Vignalensis, Wright, C. brevis, Pfr., C.scaeva, Gundl., C. rosea, 
Pfr., C. sanguinea, Pfr. 
I question the propriety of separating the groups indicated 
above by slight differences 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- 
cipally from characters of the shell. 
ANOMA, Albers, 1850. Shell elongated, turriculated, fusiform, 
subtruncated, attenuated to the summit; twelve to eighteen 
whorls, the last not free or declining, carinated at the base; aper- 
ture rounded- oblong, expanded in front; peristome thin, ex- 
panded. C. tricolor, Pfr. (xcix, 47). 14 sp. Cuba, Jamiaca, 
Mexico. 
THAUMASTIA, Albers, 1850. (Urocoptis, Beck [pt.], 1837.) Shell 
rimate, ovately cylindrical or subventricose ; whorls 8-10, regu- 
larly increasing, the last scarcely free, obsoletely carinate ; 
