COUES AND YARROW ON HERPETOLOGY. 271 



dorsal Hue, and usually other smaller ones on the sides. But the 

 markings are never bold, sometimes nearly obsolete. 



This is the most abundant and wide-ranging species of the genus, 

 occurring throughout the West east of the Eocky Mountains. The 

 specimen above noted is particularly interesting in the fact that it is 

 the northernmost one hitherto recorded, demonstrating a wider range, 

 not only of the species, but of the genus, than was before known. Mr. 

 Allen procured it on the Yellowstone, and it appears to increase in 

 numbers southward, being one of the more common serpents of 'New 

 Mexico and Arizona. I am under the impression that I saw the same 

 species beyond the Missouri watershed, at Chief Mountain Lake ; but 

 the individual was unfortunately not secured.* 



* Professor Cope, in his recent Check List, has seen tit to reduce the numbers of 

 species of this genus to four, which are readily separated into two groups as follows : — 



A. Heterodon platyrhinus. 



Reierodon ])latyrMnus subspecies atmodes. 

 With the azygos behind the rostral plate in contact with the frontal plates. 



B. Heterodon simus subspecies simus. 



Heterodon simus subspecies nascius. 

 With the azygos behind the rostral plate separated by a varying number of 

 small plates. 

 In this connection, it may be mentioned that if color should be taken into considera- 

 tion as a specific marking, it seems that Baird and Girard's H. niger should be admitted 

 as a subspecies of H. platyrhinus, for not only is there a very marked difference of col- 

 oration (some species of H. niger being entirely black), but as a rule the rostral of H. 

 niger is much more developed than that of H. platyrhinus, and the dorsal carina are 

 acute and very well marked, and there are obvious differences in the size of the scales. 

 It is true that in examining a number of specimens of H. platyrhinus, H. niger, and 

 H. atmodes, it will be found that a regular intergradation of color exists ; but if atmodes 

 is to be admitted as a good and valid subspecies of H. platyrhinus, it would seem that 

 H. niger is entitled to the same respect. In an examiuation of the different specimens of 

 Heterodon in the National Museum, Smithsonian Institution, the authors were fortunate 

 enough to discover a species called Heterodon kennerlyi by Kennicott, in the Proceed- 

 ings of the Acad, of Nat. Sci. Phila., 1860, pp. 336 and 337 ; and as after a careful exam- 

 ination of several specimens, the specific characters of them compare entirely with the 

 type, the entire description is here given. The species naturally falls near the B. or 

 simus group, in which the azygos is separated from the frontals, not by a varying num- 

 ber of plates, but by exactly two plates in five specimens and by three in one speci- 

 men. These specimens are from the following localities : — 



1282. Matamoras, Texas. 



7290. Lower Rio Grande. 



5185. Fort Stockton, Texas. 



8878. Southern Arizona. 



8413. Southern Arizona. 

 A comparison of these specimens with eighteen well-marked species of H. simus 

 wasicMS shows that although these latter vary as to the number of scales separating 

 the azygos and frontals, in no respect does it approach the regularity and systematic 

 arrangement of the scales in H. simus kennerlyi. 



Heterodon simus kennerlyi. {Kennic) C. 4' y- 

 H. kennerlyi, Kennicott. 



Spec. char. — Head broad, very .short anteriorly. Rostral plate very large. Loral 

 plate very small, sometimes absent. Only two supplemental plates behind the azygos ; 



