Casey — Notes on the Pleurotomidae. 163 
body whorls measures 27 mm. in length and 12.5 mm. in 
width. The embryo is of the same general type as in Pseu- 
dotoma, as figured by Cossmann. 
Fusitoma 0D. gen. 
The type of this genus is Pusttoma sipho, a rather elon- 
gate, fusiform and moderately stout shell with somewhat 
thin walls, originally assigned to the genus /usus. The 
aperture is feebly oblique and half as long as the shell, the 
canal very short and not differentiated from the aperture, 
of which it forms the gradually narrowed anterior end. The 
base is very gradually and sinuately narrowed below the 
broad convexity of the body whorl. The body whorls are 
broadly convex, becoming concave above near the suture, the 
latter feebly margined beneath. The ribs are obsolete, being 
replaced by long fine elevated lines apparently produced by 
arrested growth and crossed by somewhat conspicuous lyra- 
tion. The embryo in my single example — which I owe to 
the kindness of Mr. Aldrich — is not in good condition, so that 
I cannot venture to describe it. 
There have been some other species described and figured 
from the American Eocene, which may form genera in this 
tribe or enter some of those already defined and particularly 
Fusitoma; among these may be mentioned Pl. leania and 
Pleurotomella sigma, of Harris, Pleurotoma capax Whitf., 
Fusus whitfieldi Ald., and perhaps Fusus harrisi, of the 
latter author. I have not been able to study any of these 
species except by published drawings and descriptions. 
DoONOVANIINI. 
The genus Donovania Bucq. (= Lachesis Risso; nom. 
praeocc.) is one of those doubtful forms which have been as- 
signed widely different positions in the Gastropod series, and 
is included here as forming a distinct tribe of Pleurotomidae 
merely for the sake of completeness, and not because I have 
been able to make any investigations leading to personal con- 
