l8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I25 



frequently is not visible in the aperture. The sculpture, both axial 

 and spiral, ranges from obsolete to strongly incised lines or raised 

 lamellae. 



Type: Turbonilla typica Dall and Bartsch. 



KEY TO THE SUBGENERA OF TURBONILLA 



Axial ribs and incised intercostal spaces extending over the base to 

 the umbilicus Turbonilla 



Axial ribs and incised intercostal spaces terminating at the periph- 

 ery Chemnitsia 



Subgenus Chemnitzia d'Orbigny 



1839. Chemnitsia d'Orbigny, In Webb and Berthelot, Histoire naturelle des 



lies Canaries, vol. 2, pt. 2, Mollusques, p. 77. 

 1861. Euturbonilla Semper (part), Arch. Ver. Freunde Naturg. Mecklenberg, 



vol. 15, pp. 354-361 (no type). 

 1874. Microbelisciis Sandberger, Die Land- und Susswasser-Conchylien der 



Vorwelt, p. 690 (type: Turbonilla (Microbeliscus) inaspectus Fuchs). 



Turbonillas without spiral sculpture, having prominent axial ribs 

 which fuse or terminate at the periphery. The intercostal spaces are 

 deep and sunken and terminate at the periphery, extending upward 

 to the summits of the whorls. Base smooth, devoid of all sculpture. 

 Columella straight. 



Type : Melania campanellae Philippi. 



KEY TO THE SPECIES OF THE SUBGENUS CHEMNITZIA 



Periphery appearing as a spiral cord acisi 



Periphery not appearing as a spiral cord. 

 Whorls strongly rounded. 



Shell large admeta 



Shell small geryoni 



Whorls only moderately rounded. 

 Shell large. 



Axial ribs protractive hippolyta 



Axial ribs vertical adonisi 



Shell small. 



Shell slender alcmena 



Shell stout iolausi 



Whorls flattened, not moderately rounded. 

 Shell large. 



Axial ribs vertical hydra 



Axial ribs protractive atigeasi 



