554 PROCEEDIXGS OF THE ACADEMY OF [Aug.. 



Arojnochelys carinatus Storeria dekayiE. 

 Terrapene Carolina Carolina E. occipitomaculata E. 



Carolina triunguis Haldca striatula E. 



Testudo polyphcynus Spilotes corais couperi 



Anolis principalis Heterodon platyrhiniis E. 



Sceloporus undulatus E. Ophibohis doliatus doliatus E. 

 Liolcpisma laterale E. doliatus coccineus 



Ophisaurus ventralis Virginia elegans 



Eimieces quinquelineatus Sistrurus ^niliarius 



Eutcenia sirtalis sirtalis E. Crotalus horridus E. 



Of the above, Aromochelys carinatus, Tropidonotus grahami and 

 Virginia elegans are not known east of the Loiiisianian district. 



IV. — Austroriparian species, which extend west of longitude 98° in 

 Texas : 



Chrysemys mohiliensis Ancistrodon piscivorus 



Zamenis flagellum flagellum Flaps fulvius 

 Tropidonotus rhomhijer 



To these are to be added Cnemidophorus sexlineatus, Cyclophis 

 (Bstivus, Liopeltis vernalis and Ancistrodon contortrix, which are also 

 Eastern and to some extent Central. 



V. — Neotropical intrusions : 



Dryniohius margaritiferus Sihon septentrionale 



Erythrola mprus imperialis 



It is seen that seventy-three Sonoran species practically fail to range 

 east of longitude 96° in Texas, while but seven pass eastward to any 

 distance beyond that meridian, five of these entering the western part 

 only of the Austroriparian, while the two others are exceedingly 

 rare east of the Mississippi river. 



Of species which belong to the Austroriparian and Eastern, twenty- 

 four w^hich enter Texas do not extend much beyond longitude 98°, 

 while but nine pass beyond it into western Texas, and of these three 

 are of aquatic habits and four more are widely ranging forms. 



If anything is made clear, therefore, by a study of these lists, it is 

 that the zone of change between the eastern and the western faunas is 

 this north and south belt lying approximately between the 96th and 

 98th meridians. This area nearly coincides with that in which the 

 heavy rainfall of the Gulf Coast drops to below thirty inches annually, 

 and lies somewhat eastward of where the arid region may properly be 

 said to begin, the line of twenty inches rainfall being just west of the 



