Vi GEOGRAPHIC DISTRIBUTION OP THE ACHATINIOE. 



(Obeliscus phylum.) 



Neobeliscus, xviii, 280. Euonyma, xviii, 38. 



Obeliscus, xviii, 240. Tortaxis, xviii, 5. 



S.g.Protobeliscus, xviii, 251. ? Synapterpes, xviii, 227. 



" Stenogyra, xviii, 258. S. g. Promoussonius, xviii, 



" Pseudobalea, xviii, 271. 230. 



" Lyobasis, xviii, 274. S. g. Chryserpes, xviii, 231. 



Rhodea, xviii, 234. " Zoniferella, xviii, 233. 



Subfamily CCELIAXIN^ (Vol. XVIII, p. 330.) 



Cryptelasmus, xviii, 331. Distcechia, xviii, 335. 



Thomea, xviii, 333. Cceliaxis, xviii, 336. 

 Pyrgina, xviii, 334. 



GEOGRAPHIC DISTRIBUTION OF THE 

 ACHATINIDJB. 



The distribution of Achatinidse indicates an African center 

 of evolution where the group probably originated, and in 

 which the main phyla and genera had their rise. The early 

 members of the family are unknown or have not been 

 recognized. They are to be looked for in mid-mesozoic 

 deposits, with their allies the ancestral Megaspiridcz and 

 Clausiliidce. From the African center, Stenogyrine and Coeli- 

 axine Achatinidae migrated to South America before the in- 

 terruption of land communication across the tropical Atlan- 

 tic. Later, the radiation of Stenogyrinse extended to India 

 and the East Indies. This probably took place in the north 

 of Africa, above the area in which the subfamily Achatinina 

 had meantime arisen. The Achatinincz have probably never 

 extended beyond their present area, being unknown in Euro- 

 pean or Indian tertiary strata, or in the recent fauna out- 

 side of tropical and South Africa and Madagascar, except 

 where recently imported. They are a lateral branch from 

 the more primitive Stenogyrine. 



The Cceliaxmce are obviously an ancient group evolved in 

 mesozoic time, and now approaching extinction. 



