Casey — Notes on the Pleuwrotomidae. 161 
PSEUDOTOMINI. 
This tribe, composed exclusively of extinct old Tertiary 
types, is confessedly somewhat artificial in scope. There is 
a certain general Fusoid habitus common to all, the shell being 
usually stout in form, with short or obsolete beak and the 
outer lip is broadly, feebly sinuate posteriorly to the suture, but 
without a clearly limited notch. Pseudotoma was placed among 
the Conidae by Cossmann and Cordiera in the Pleurotomidae. 
Fusitoma sipho Ald., was described by its author as /usus 
siphus and Varicobela smithi Ald., was originally described 
under the name Strombus smithi, while other species, brought 
together to form the present tribe, were originally assigned to 
Fusus, Mitra and Borsonia, showing the doubt and uncer- 
tainty involving the relationships of the species. My concep- 
tion of Cordiera is derived from the study of a small species 
from the ‘‘ Caleaire grossiére,’’ labeled Pl. nodularis Desh., 
and, if it is a typical representative of that genus as main- 
tained by Cossmann, there can be no doubt whatever of its 
very pronounced affinity with our Mitra biconica, of Whitfield, 
and Borsonia ludoviciana Vgn., which species may be con- 
sidered as representing Cordiera for the present. As to the 
relationship between Oordiera and Borsonia, I am forced to 
assume that there is very little real affinity, but only a super- 
ficially apparent affiliation due to the plication of the colu- 
mella, a character which is frequently sporadic and of little 
orno phylogenetic significance in the Pleurotomidae. Although 
the embryo of our Eocene Pleurotoma heilprini Ald., differs 
noticeably from that characterizing the European type of 
Pseudotoma, the remaining features of the shell agree very 
well, and we may conclude that hezlpriné represents the genus 
in the American Tertiary, but the species figured by Cossmann 
under the name Pseudotoma bonellii, is certainly generically 
different from Ps. intorta Broc., assumed as typical of 
Pseudotoma. 
Ruscula n. gen. 
The general form of the shell in this genus is short and 
stout, with a very short stout reflexed beak, rather abruptly 
