336 PROCEEDINGS OF THE ACADEMY OF [1892. 



Heterodon uasicus nasicus B. & G. 



Found to be abundant in sandy soils from the heads of the Brazos 

 as far north as we went. 



Heterodon platyrhinus Latr. 



One specimen from Tule Canyon ; W. L. Black. 

 Eutaenia proxima Say, 



Specimens nearly as black as Mississippi valley specimens, from 

 Tule Canyon ; W. L. Black. 

 Eutaenia elegans marciana B. & G. 



Tule Canyon ; W. L. Black. 

 Natrix fasciata transversa Hallow. 



Common throughout the entire region, and constant in its char- 

 acters. 



Crotalophorus catenatus edwardsii B. & G. 



One specimen from Quana, Hardeman Co. on the upper Red 

 River ; W. L. Black. 



Crotalus confluentus confluentus Say. 



Abundant on the Staked Plain as far south as Canyon Blanco, 

 and on the lower country on the head-waters of the Red river. This 

 rattlesnake is abundant in prairie dog villages, as it protects itself 

 by retreating quickly into their holes when approached. 



Crotalus adamanteus atrox B. & G. 



At the foot of the Staked Plain about the heads of the Colorado. 

 Not met with on the Plain, or north of the region mentioned. 



Observations. 



The preceding list is remarkable from the absence of any species 

 of the genus Sceloporus, of which none were seen by the expedition. 

 This is due to the scarcity of timber, where they are generally found 

 in Texas. The terrestrial species of Mexico and of the Great Basin 

 do not appear to occur in this region. 



Another peculiarity is the great scarcity of individuals and species 

 of Eatcenia. I saw but one specimen during the expedition, and 

 this I did not obtain. 



As the point of junction of the Texan district with the Central 

 and Sonoran Regions, the country explored deserves especial atten- 

 tion. Enough is, however, not yet known of the distribution of 

 many of the species found within the political limits of Texas to 



