APPENDIX C. — REPTILES. 851 



of the length. The head is moderate, conical, detached from the 

 body by a somewhat contracted neck. The eyes are comparatively 

 large, occupying the middle of the length of the head. There are 

 two anterior orbital plates, the uppermost very large, vertically 

 elongated, reaching the upper surface of the head ; the lower one, 

 on the other hand, is very minute, situated between the third and 

 fourth labial shields. The postorbitals are four in number, of 

 medium, but nearly of equal size, the upper ones, however, being 

 slightly the largest. The lower one is separated from the small 

 anterior orbital by the fourth labial shield, which reaches the orbit. 



The scales of the back and sides are keeled, elliptical in form, 

 and a little more pointed posteriorly than anteriorly. On the 

 occiput they are smaller, polygonal, and smooth. 



The coloration of this snake resembles at first glance that of 

 Coluher eximius ; the ground colour is a light yellowish-brown, 

 maculated with large patches of a deeper brown, margined with 

 black, and much smaller patches of pure black. The dorsal row 

 of brown patches is considerably the largest, as in Coluher eximius. 

 On the abdomen there are two rows of small and semilunar black 

 dots, the convexity of which is turned forward. A narrow band 

 of black is seen on the upper surface of the head, in advance of 

 the eyes, extending obliquely to the angle of the mouth, being 

 only interrupted by the eye itself. 



This species was collected by General Churchill, on his march 

 to Mexico, on the left bank of the Rio Grande, at the crossing 

 near Presidio del Norte, in 1846 ; and it is with much satisfac- 

 tion that we embrace the occasion to pay a tribute of respect to 

 one, who, during the exercise of his arduous official labours, has 

 always found time for the advancement of natural history, by 

 securing specimens of whatever new or interesting species of 

 animals might fall in his way. 



Coluber mormon, Baird and Girard. 



Spec. char. — Posterior frontal plates very large; vertical plate long and very 

 narrow on its middle ; eyes very large. 



The only specimen which we have seen of this snake may prove 

 hereafter to be a young individual, as it is only one foot and a half 

 long ; but we are satisfied it will also prove to be a very distinct spe- 

 cies. The slender and conical tail forms between a third and a fourth 

 of the total length. The head is elongated and ovoidal, separated 



