CrASTEEOPODA. 293 



Shell rimate or perforate, cylindrical or oblong; aperture 

 rounded, often toothed ; * margins distant, mostly united by a 

 callous lamina. 



Animal with, a short foot, pointed behind; lower tentacles 

 short. 



Distvibution, 236 species. Greenland, Europe, Africa, India, 

 Pacific Islands, North and South America. 



Fossil, 40 species. Garb. America. (Dawson.) Eocene — . 

 Europe. 



Suh-genus. Vertigo, Miill. Y. Yenetzii, PI. XII., Pig. 17. 



Shell minute, sometimes sinistral. 



Animal with the oral tentacles rudimentary or obsolete, li 

 species. Old World. 



Spiraxis, C. B. Adams, 1850. 



Type, Achatina anomala, Pfeiffer. 



Shell ovate-oblong, fusiform, or cylindrical; last whorl 

 attenuated; aperture narrow, right margin usually inflected, 

 columella more or less contorted, base scarcely truncated, fur- 

 nished with a deeply-entering callous lamina. 



Distribution, 30 species. West Indies, Mexico, Juan Fer- 

 nandez. 



Stenogyra, Shuttleworth, 1854. Shell elongated, turreted, 

 many-whorled, semi-transparent, and blunt at the apex ; peri- 

 stome simple ; shell frequently decollated. 



Animal somewhat like Bulimus; middle rachidian teeth small. 



Distribution, 50 species. Tropical America. 



Oylutohella, L. Pfeifi'er. Cylinder-snail. 



Tijpe, C. cylindrus, PI. XII., Fig. 20. f 

 Synonyms, Brachypus, Guild. Siphonostoma, Sw 

 Shell cylindrical or pupiform, sometimes sinistral, many- 

 whorled, apex of the adult truncated, aperture round, peristome 

 continuous, expanded. 



Animal similar to clausilia ; foot short, oral tentacles minute. 

 Distribution, 143 species. West Indies, Mexico, Texas, South 

 America. 



BALfeA, Prideaux 

 Type, B. perversa. PI. XIL, Pig. 21. 

 Synonym, Pusulus, Pitz. 



* Dr. Pfeiffer terms those teeth parietal -which are situated on the body-whorl, these 

 on the outer lip -palatal, and on the inner lip columellar. 



t The figure is taken from a specimen in Mr. Cuming's cabinet, in whicli the 

 empty apex, usually decollated, remains attached to the adult shell. 



