TO GEOLOGY. 167 
Observations. This isa much smaller species than the 
last, and its sharp transverse strie, which are much more 
distant, together with the folded columella, render it im- 
possible to confound them. 
T. venusta. Plate 5. Fig. 173. 
Description. Shell subulate, very much attenuated, 
with close longitudinal ribs and minute transverse striz in 
the intermediate spaces; substance of the shell thin; 
spire very much elevated, acutely pointed; suture linear ; 
whorls fifteen, flattened; mouth narrow; columella smooth ; 
outer lip 
Length 13-20ths, Breadth 3-20ths, of an inch. 
Observations. A very distinct species from the above, 
being more attenuate, having a smooth columella, and 
being more closely ribbed. The transverse striz, inter- 
mediate between the ribs, are very minute, while in the 
above two species they are larger and cross the ribs. 
Four species of this genus have been observed in Eng- 
land: three species in the Oolitic Group and one in the 
London Clay. Sixteen are given for the Tertiary by M. 
Deshayes. Ten of these are found at Baden (Miocene), 
and seven at Bourdeaux (Miocene). In the Tertiary of 
Maryland Mr Conrad has observed one species, which he 
calls simplex, being the only one heretofore observed in our 
Formations. 
