OLEACINID^E. 21 



Genus PSEUDOSTJBULINA, Strebel and Pfeffer, 1882. 



Shell turriculated, narrow, longitudinally plicate-striate, whorls 

 numerous, forming a long spire, last whorl rather small com- 

 pared to the length of the shell ; columella truncated at the 

 base ; peristome simple ; aperture small. Mexico. 



The shells resemble Subulina, from which it may perhaps be 

 distinguished by its ribs and button-like apex, but the animal 

 has no jaw (agnathous). 



Genus VOLUTAXIS, Strebel and Pfeffer, 1882. 



Columella with a basal fold ; not truncate ; whorls, including 

 the embryonal ones, longitudinally ribbed. Differs from the 

 preceding group in apex and columella. It is difficult to 

 separate this and the preceding group conchologically from 

 Subulina and Spiraxis ; indeed, I would not attempt to do this. I 

 have included here merely the species which Strebel places in 

 these new groups, partly from his examination of their lingual 

 dentition, partly from the analogy of external features. The 

 dentition of too few of the species of Spiraxiform shells has 

 been examined to permit any generalizations. It should be 

 remarked that several Stenogyrse examined by Binney possessed 

 the characters which entitle them to their usually assigned posi- 

 tion, whilst a single Spiraxis from Haiti was without jaw, and 

 had the Glandiniform dentition. 



Genus RAVENIA, Crosse, 1873. 



Shell allied to Yolutaxis, minute, imperforate, subhyaline, 

 columella spirally twisted, outer lip bent inwards, and armed 

 with a strong tooth in the middle. 1 species. 



Los Roques, near Curapoa, West Indies. 



