COUES AND YARROW ON HERPETOLOGY. 285 



The typical and best known species of this genus is the common 

 Black Snake of the United States {B. constrictor). All the species agree 

 in their slender form and perfectly smooth, lustrous scales and uniform 

 coloration while adult, though the young are somewhat particolored. 

 They grow to a large size, and are noted for their powers of constriction. 

 They are among the most active and agile of our serpents, possessing 

 eminent scansorial powers, and are persistent enemies of numerous small 

 birds, whose nests they rob of the eggs or young. 



Oyclophis vernalis. {BeK.) Ounth. 



Coluber vernalis, DeKay, MS. — H.vrl. Journ. Acad. Nat. Sci. Phila. v. 1827, 361 ; Med. 



and Phys. Res. 1835, 124.— Storer, Rep. Mass. Rept. 1839, 224.— Holbr. N. Am. 



Herpet. iii. 1842, 79, pi. 17.— DeKay, N. Y. Fauna, iii. 1842, 40, pi. 11. f. 22.— 



Thomps. Nat. Hist. Vermont, 1842, 117. 

 Chlorosoma vernalis, Bd. & GiR. Catal. N. Am. Rept. 1853, lOS. 

 Herpetodryas vernalis. Hallow. Proc. Acad. Nat. Sci. Phila. 1856, 243. 

 Liopeltis vernalis, Cope, Proc. Acad. Nat. Sci. Phila. 1860, 560. — Hayd. Trans. Amer. 



Phil. Soc. xii. 1882, 177. 

 Cyelophis vernalis, Gunther, Cat. Col. Snakes Brit. Mus. 1853, 119. 



Observed by Dr. Hayden on the Yellowstone. 



In vol. V, Zoology, of Ex. for Expl. West of One Hundredth Meridian, 

 mention is made by Dr. Yarrow, p. 539, of the discovery of this species 

 at Abiquiu, X. Mex., and in the Am. Xat. vol. — , p. — , the same author 

 relates that it was found by Lieutenant Carpenter in Colorado. These 

 facts extend greatly its southern limit. C. cestivus, the Easterti and 

 Southern species, has been found in New Mexico, Texas, and Western 

 Missouri. 



The two species are readily distinguishable : C. vernalis having 15 

 rows of smooth scales, 7 upper labials, 8 lower; and G. cestivus having 

 17 rows of strongly carinated scales, except the outer row, which is 

 smooth, and the second slightly keeled; upper labials 7, lower labials 8. 



SAURIA. 



Family IGUANID^. 



Genus PHRYNOSOMA. Wieg. 



Phrtnosoma douglassi. (Bell) Gray. 



Sorned Lizard; Rorned ^^ Toad"; Horned '■^Frog^. 



a. DOUGLASSI. 



Agama douglassii, Bell, Trans. Linn. Soc. xvi. 1829, 105, pi. 10. — Bell, Isis, Bd. xxiii. 

 1H30, 910.— Harl. Mad. and Phys. Res. 1835, !4l, f. 3. 



Fhrynosoma douglassii, Gray, Griffith's An. King. ix. 1831, 44. — Wagl. Nat. Syst. Amph 

 1830, 146.— WiEGM. Herp. Mex. 1834, 54.— Holb. N. Am. Herpet. i. 1842, 101, 

 pi. 14. — Gray, Cat. Br. Mas. 1845, 227.— Girard, Stansbury's Rep. Expl. Great 

 Salt Lake, 1852,362, pl.7, f.6-9 (monographic).- Coi'E, Proc. Acad. Nat. Sci. 

 Phila., 1866, 302.— Allen, Proc. Bost. Soc. Nat. Hist. xvii. 1874, 69. 



