THE NAUTILUS. 93 
gins, though less pronounced; teeth small and delicately cut, 
not confined to aperture, all extending evenly over a narrow 
zone of the base. 
The largest and the smallest of five specimens, dredged from 
Honolulu harbor channel in 1915, measure in length 20 and 
14 mm. respectively. The shells were all dead, but in a good 
state of preservation. 
Type, one specimen in the author’s collection. 
REVIEW OF THE THYSANOPHORA PLAGIOPTYCHA GROUP. 
BY H. A. PILSBRY. 
In the course of identifying specimens of this group from 
Mexico and Panama it became necessary to examine all of the 
material in the collection of the Academy, some 46 lots of from 
one to several hundred specimens each. As some synonymy is 
involved, it may be well to put the results on record. 
Fig. 1. Thysanophora fuscula (C. B. Ad.), Jamaica. Fig. 2, 
T. plagioptycha (Shuttl.), Humacao, Porto Rico. Fig. 3, T. 
plagioptycha, Fikahatchee Key, Florida. Fig. 4, T. cxcoides 
(Tate), Panama City. 
These forms were considered to belong to the genus Acanth- 
inula by Strebel and some other authors. The sculpture, how- 
ever, is only superficially like that genus, but exactly like such 
