86 REPTILES. 



variable in number. Scales keeled, small. Anal entire. Teeth 

 equal, smooth. Ground colour whitish, with a dorsal series of 

 large quadrangular brown spots. America. 



Pituophis, Holbr. N. Amer. Herpet. iv. p. 7 ; Baird fy Girard, 

 Catal. p. 64 ; Dum. 8f Bibr. p. 232. Coluber, sp., Daud. Rept. 

 vi.p.409; Harlan, Journ. Acad. Nat. Sc.Philad.\827 ; Blainville, 

 Nouv. Ann. d'Hist. Nat. 1835. 



The separation of the specimens of this genus into species is 

 attended with great difficulty, and we freely confess the follow- 

 ing diagnoses are uncertain, as we think the species lately founded 

 by herpetologists. Having only a few specimens in the collection, 

 we are not able to unravel the contradictions between the Erpe- 

 tologie generate and the descriptions of Baird and Girard, espe- 

 cially as not one of our specimens quite agrees with those descrip- 

 tions. But we feel certain that the number of the posterior 

 oculars is liable to great variation (2-5), not only in the different 

 specimens of one species, but often in the two sides of the same 

 individual. 



1. Pituophis vertebralis. 



Coluber vertebralis, Blainville, Nouv. Ann. Mus. d'Hist. Nat. 

 1835, pi. 27. f. 2; Baird § Girard, Catal. p. 152 (not Bum. <y 

 Bibr. p. 238). 



Scales in twenty-seven to twenty-nine rows ; shields of crown 

 regular ; rostral nearly as broad as high ; eight upper labials ; one 

 anterior ocular. 



a. Adult. Mexico. From M. Salle's Collection. 



b. Half-grown. Mexico. From M. Salle's Collection. 



c. Adult. Mexico. From the Haslar Collection. 

 (I. Adult. Mexico. 



2. Pituophis melanoleucus. 



Coluber melanoleucus, Daud. Rept. vi. p. 409 ; Harl. Journ. 

 Acad. Nat. Sc. Philad. 1827, p. 359, and Med. Phys. Res. 1835, 

 p. 122; Bartram, Trav. Carol, p. 276. Pituophis melanoleucus, 

 Holbr. N. Amer. Herpet. iv. pi. 1 ; Baird fy Girard, Catal. p. 65 ; 

 Dum. <§r Bibr. p. 233. 



Scales in twenty-nine rows ; each posterior frontal divided into 

 two ; rostral nearly as broad as high ; eight upper labials ; one 

 anterior, three posterior oculars. 



a. Young. America. 



