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ZOOLOGY BATRACHIANS AND REPTILES. 



While in Arizona, Dr. Coues discovered a new and beautiful species 

 of Crotalus (Plate xxii), which Professor Cope has described, and named 

 Crotalus pyrrlms. It is the most brilliantly coloi-ed of its genus, and is allied 

 to C. mitchellii. This serpent was not seen by the survey. 



Through the investigation of this genus by Professor Cope, we are now 

 acquainted with eighteen species in all belonging to it, although one or two 

 still remain to be identified. From his paper on the subject, a list is given 

 as follows ; but this list has since been reduced according to his new Check- 

 List of N. A. Batrachia and Reptilia, published by the Smithsonian Institution. 



The intensity of the distribution of these serpents is the region of Lower 

 California, Upper Sonora, and Arizona, which has seven peculiar species, and 

 three which enter from the neighboring districts. As the literature on this 

 genus is much scattered, it is deemed advisable to give a synopsis according 

 to Professor Cope. 



" The genus divides itself into two natural sections : 



" I. Top of muzzle covered by three pairs of symmetrical shields in contact ; 



nasals distinct : 

 " a. Rattle acuminate : 



" C.durissus, Linn. Scales in 29 rows ; 4 rows scales below 

 orbit : yellow, with two brown longitudinal bands on anterior 

 part of body, remainder with black rhombs embracing yellow 

 centers. Sonora and Mexico, to Vera Cruz. 



" C. terrificus, Laurenti. 4 rowsof scales below orbit: brown, 

 with two darker bands above anteriorly, and a series of large, 

 darker dorsal rhombs, with yellow outlines. Brazil, Mexico. 



' ' C. basiliscus, Cope. 2 and 3 rows of scales below eye ; rows 

 on body 29 ; labials 14 : yellow-brown, with large adjacent 

 chestnut ; red-yellow bordered dorsal rhombs, alternating witli 

 chestnut spots ; no longitudinal bands anteriorly. Western 

 Mexico. 



