272 BULLETIN UNITED STATES GEOLOGICAL SUEVEY. 



Geuus EUT^NIA. Baird & Girard. 



Coluber, Tropidonotus, sp., AuCT. 



Eutainia, Baird & Girard, Cat. N. Am. Eeptiles, 1853. 



Eutainia, emend. 



To the few species of this geuus known to the older authors under 

 the names of Coluber or Tropidonotus, many were added, in 1853, by 

 Baird and Girard, at the date of establishment of the genus Uutcenia, a 

 majority of the fifteen species described in the catalogue of the authors 



the latter is sometimes replaced by two symaietrical contiguous plates, and without any 

 supplemental. The prenasal and prefrontal in contact with the posterior process of 

 the rostral. Dorsal row of scales twenty-three, all carinated except the first and sec- 

 ond, which are perfectly smooth. Ground-color light yellowish gray ; a dorsal series 

 of rather indistinct, rounded or subquadrate, brown blotches ; a second series of smaller, 

 circular spots, much darker and more distinct ; below this a third and more indistinct 

 series. 



Descr. — In its general form and appearance, this resembles the H. nasicus, with 

 which it is sometimes found associated. The body, however, is rather shorter and 

 thicker than in H. nasicus, and tbe head is broader, with the part of the head anterior 

 to the eye decidedly shorter. The nasals are not as well developed longitudinally as 

 in H. nasicus, but the result of this shortness of the anterior part of the head is seen 

 in the very small loral, which is frequently wanting entirely. There is never more 

 than one loral, while frequently two are seen in R. nasicus, in which the loral is la 

 every case strikingly larger than in kennerlyi. The most striking difference between 

 these species is in the number of small plates surrounding the azygos or postrostral. 

 While in H. nasicus there are always at least ten of these, one or two of which margin 

 the inner edges of the prenasals and prefrontals, there are never more than two, and 

 frequently but one additional plate, in S. kennerlyi, and the prenasal and prefrontal 

 are always in contact with the posterior process of the rostral. The azygos is short, 

 nearly as broad as long, and usually there are just behind it two contiguous plates of 

 about the same size, separating it from the postfrontal, but not from the prefrontal. 

 Frequently, however, the azygos is longitudinally divided, and without any additional 

 plates, but in contact witli the rostral anteriorly, and the vertical posteriorly, and not 

 separated from the postfrontals. The Tertical, occipitals, superciliaries, and labials 

 are much as in H. nasicus, though generally less developed longitudinally. The rostral 

 is as large as in H. nasicus. The two outer dorsal rows are both perfectly smooth ; in 

 H. nasicus, the second is distinctly though delicately carinate. 



The ground-color is light yellowish-gray, with a dorsal series of rather indistinct 

 subquadrate or rounded blotches, two to two and a half scales long, and separated by 

 intervals of one or two scales, rather wider anteriorly. Below this is a series of very 

 distinct, purplish-black, circular blotches, covering four scales transversely and two 

 longitudinally ; below this one or more indistinct series of spots. This pattern of col- 

 oration is very similar to that of H. nasicus, but the ground-color is always lighter, and 

 the dorsal spots are lighter and less distinct. The upper lateral series is of a purplish- 

 black, and much more di-tinct, forming a prominent character. 



Abdomen nearly entirely black, except a few yellow scuta. The head is marked as 

 in H. nasicus, except that the nasals, prefrontals, and rostral are all yellowish ; while, 

 in the latter species, they are dark in front of the light transverse line which crosses 

 the crown behind the rostral; and, in H. kennerlyi, the light line across the superci- 

 liaries and vertical is much broader than in H. nasicus. This species differs from R. 

 simus in mauy of the same features as does R. nasicus. These, together with the small 

 or absent loral and small number of supplemental plates, will readily distinguish it. 



Rio Grande {Dr. Ktnnerly). Sonora. 



