ON THE ZOOLOGICAL POSITION OF TEXAS. 47 



While coDsideriDg the boundaries of the Sonoran region I allude to 

 its southern limit. A collection made by Edward Wilkinson at Batopilas, 

 in Southern Chihuahua, includes a majority of species of this fauna. 

 These are Phrynosoma cornutum^ TJta ornata, Sceloporus coitcJii, S. 

 tristiehiis, Euiaiiia cyrtopsis, Phimotliyra gmliamke, JElaps euryxantJms. 

 Accessions from the Mexican faunce are only Anolis nehulosus and Cyclura 

 acanthura of general distribution, and Trimorphodon upsilon heretofore 

 from the west side of the j)lateau of Mexico. A peculiar snake is Pro- 

 clmira wmula.* 



Collections sent by Dr. Alfredo Duges from Guadalaxara, at the 

 southern extremity of the northern plateau of Mexico, included five dis- 

 tinctive species of the Sonoran region, viz, Bufo punctatns, Hyla areni- 

 color^ Spea hammondi, Eutcenia cyrtopsis, and Hypsiglena ochrorhynchus. 

 Ten other species belong to Nearctic genera, while one only, ( CystignatJms 

 microtis) belongs to an exclusively Neotropical genus. There are about 

 a dozen species peculiar to the neigliborhood. 



In the Check List of the Keptilia and Batrachia of North America I 

 attempted to define the Texan district of the Austroripariau region as 

 distinct from the two other divisions of the same, the Louisianian and 

 the Floridian, and gave a list of the genera and species, supposed to 

 characterize it. I remarked (p. 80) that "the high iiortliwestern regions 

 of the State should be assigned to the Sonoran fauna," but not being 

 aware at that time of the distribution of many species, I did not give 

 this region siiflicient extent. lu accordance with the facts already ad- 

 duced, it seems necessary to restrict this Texan district to the south- 

 western part of the State, and regard it as characterized by the list of 

 species already given in the first column on page 44. I select from 

 that list the following species which are, so far as now known, i^eculiar 

 to it: Testudo herlandieri, HolbrooMa propinqua, Enmcccs tetragrammus 

 Rliadincca imperiaUs, Dlemyctylus meridionaUs. 



The Texan district will then be distinguished by the presence of these 

 species, and the admixture of the following Mexican species: Uncia 

 onca, Fells pardalis, Dasypus pcha, Bicotyles torquatus, Sceloporus scalaris, 

 Sihon annulatns, Smilisca haudina, Bufo valUceps. 



* Eleventh Contribution to the Herpetology of Tropical America, by E. D. Cope, 



Proceed. Amer. Philos. Society, June, 1879. 



