TO GEOLOGY. 135 
P. Desnoyersii.* Plate 4. Fig. 128. 
Description. Shell fusiform, turrited, closely and trans- 
versely striate, slightly tuberculate on the superior whorls ; 
substance of the shell rather thick; spire elevated, pointed 
at the apex ; whorls eight ; mouth two fifths the length of 
the shell. 
Length .7, Breadth 5-20ths, of an inch. 
Observations. In outline somewhat like the last de- 
scribed, but differing in the striz and tubercles. In the 
Desnoyersii the transverse strize are disposed to alternate, 
and are cut by almost imperceptible longitudinal strie. 
P. Heninghausii.t Plate 4. Fig. 129. 
Description. Shell fusiform, turrited, transversely striate, 
- furnished with two rows of longitudinal folds in zig-zag ; 
substance of the shell rather thin ; spire elevated, acute at 
apex; whorls ten, subcanaliculate above ; mouth rather 
narrow, about one third the length of the shell. 
Length .7, Breadth .4, of an inch. 
Observations. This species may be distinguished by its 
double row of folds, which being placed, the superior one 
obliquely to the right, the other to the left, produce a zig- 
zag appearance. 
* Named after M. Desnoyers, advantageously known for his labours in 
the Tertiary deposites. 
+ Named after the distinguished geologist of Crefeld. 
