1903.] NATURAL SCIENCES OF PHILADELPHIA. 551 



Rhinochilus lecontii B. & G. 

 Heterodon nasicus B. & G. 

 Tantilla nigriceps Kenn. 



The one specimen received had the ventral surface pinkish-salmon 

 color in life. 

 Elaps fulvius (L.). 



One specimen received. 

 Ancistrodon oontortrix (L.)- 



One specimen received. 



Crotalus atrox atrox B. & G. 

 Crotalus confluentus Say. 



The Fauxal Relations of Texas Reptiles. 



An attempt to determine the elements composing the local fauna 

 above noticed, has led to a study of the reptiles of the entire State of 

 Texas, the result of which is, in my belief, to establish three facts, 

 hitherto not wholly free from uncertainty: first, that the boundary 

 between the Austroriparian and Sonoran reptilian faunas lies approxi- 

 mately between the ninety-sixth and the ninety-eighth meridians of 

 longitude in Texas; second, that the restricted Texan district of Cope 

 is not Austroriparian but Sonoran; third, that transcontinental zones 

 of distribution can not be maintained in the Medicolumbian region for 

 reptiles. 



In his final essay upon the life regions of North America, determined 

 mainly by a study of reptiles and batrachians, Prof. Cope^ placed the 

 portion of Texas extending from the high lands east of the Pecos river 

 to a north and south line about the longitude of Austin, in his Texan 

 district of the Austroriparian subregion, and the portion east of it, in 

 the Louisianian district. Western Texas he attached to his Chihuahuan 

 district of the Sonoran subregion, which included the higher portion of 

 central and northern Mexico, and stretched west through southern 

 New Mexico and Arizona to southern and Lower California. The 

 great plains from northern Texas, east of the Rocky Mountains, ex- 

 cepting the east and west river bottoms, he called the Central district 

 of the vSonoran. 



Dr. C. Hart Merriam,* basing his conclusions chiefly upon the distri- 

 bution of plants and mammals, established more or less parallel zones 

 stretching completely across the continent from the Atlantic to the 

 Pacific, the greater part of temperate North America being occupied 



''Rep. U. S. Nat. Mus., 1898, pp. 1199-1234. 



''Proc. Bio. Soc. of Wash., 1892, Vol. VII; and Nat. Geog. Mag., 1894. 



