50 THE NAUTILUS. 



SYNOPSIS OF THE SUBDIVISIONS OF HOLOSP1RA AND SOME RELATED 



GENERA. 



BY W. H. DALL. 



Genus HOLOSPIRA Martens ; type H. pilocerei Pfr. 



Subgenus Holospim s. s. 



Axis large, with an internal fold in the penultimate whorl and 

 with a parietal, basal and peripheral lamina projecting into the 

 lumen of that whorl. Besides the type, this includes H. goldfussi 

 Menke and H. goniostoma Pfr. 



Section Bostrichocentrum Strebel & Pfeffer, 1880. 



Axis moderate, with a continuous plait, except in the last part of 

 the last whorl ; no lamina?. Type H. tryoni Pfr. H. Veracruz i mix 

 Dall belongs here. 



Section Haplostemma Dall, 1895. 



Axis moderate, with, in the penultimate whorl only, a short, 

 stout axial lamina extending about half a gyration, but no other 

 laminre. Type H. mearnsii Ball, New Mexico. 



Section Eudistemma Dall, 1895. 



Penultimate whorl with a parietal and a short axial lamina only, 

 axis moderate. Type H. arizonensis Stearns. 



Section Distomospira Dall, 1895. 



Penultimate whorl with a basal and a short, strong axial lamina 

 only, axis moderate. Type H. bilamellatn Dall, New Mexico. 



Subgenus Metattoma Strebel & Pfeffer, 1880. 



Axis smooth, without plaits, penultimate whorl without internal 

 lamina?. Type H. nemeri Pfr. This includes also H. pasonis Dall, 

 If. coahuilensis Binn., H. semisculpta Stearns, H. pfeifferi Meuke, H, 

 remondii Gabb., H. crossei Dall, H. pilsbryi Dall. 



Subgeuus Ccelostemma Dall, 1895. 



Axis vertically ribbed as in Ccclocentntm, shell otherwise as in 

 JUetastoma. Type H. elizabetlue Pilsbry. 



The internal characters of the following species are unknown : 

 H. gealei A. Ads., H. imbricata Martens, H. cretacea Pfr., H. micro- 

 stoma Pfr. and H. terete Menke. 



