Vi GEOGRAPHIC DISTRIBUTION OP THE ACHATINIDAE. 



(Obeliseus phylum.} 



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



Obeliseus, xviii, 240. Tortaxis, xviii, 5. 



S.g. Prot obeliscus, xviii, 251. ? Synapterpes, xviii, 227. 



" Stcnogyra, 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. Distoechia, xviii, 335. 



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

 Pyrgina, xviii, 334. 



GEOGRAPHIC DISTRIBUTION OF THE 

 ACHATINID^E. 



The distribution of Achatinidae 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 Megaspiridce and 

 Clausiliidce. From the African center, Stenogyrine and Cceli- 

 axine Achatinidoe migrated to South America before the in- 

 terruption of land communication across the tropical Atlan- 

 tic. Later, the radiation of StenogyrinaB extended to India 

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

 of Africa, above the area in which the subfamily Achatinince 

 had meantime arisen. The Achatinince 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 Stenogyrince. 



The Cccliaxincc are obviously an ancient group evolved in 

 mesozoic time, and now approaching extinction. 



