THE NAUTILUS. 



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 

 t4ate of preservation. 



Type, one specimen in the author's collection. 



REVIEW OF THE THYS&HOPHORA 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 fmcula (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 



