284 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



The genus OpMbolus comprises a considerable number of species of 

 very handsomely marked serpents, in all of which a black, brown, or red 

 ground is crossed by light markings. The Ophibolus getulus is a com- 

 mon Eastern species, black like the present, and ringed with yellow, but 

 the rings bifurcate on the sides. 



Ophibolus multistrata. (Kenn.) 



Lampropeltis muUistriata, Kenn. Proc. Acad. Nat. Sci. Phila. 1860, 328. (By err. typog. 

 for multistrata. " Fort Lookout, Nebraska ", by err. for Fort Benton, Mon- 

 tana.) — Hayden, Trans. Amer. Pbil. Soc. xii. 1862, 177 (Fort Benton). 



Ophibolus multistratus, Cope, Check List N. A. Bat. and Eep. 1875, 37. 



The locality of the original specimen is stated by its discoverer to be 

 Fort Benton, Montana, not " Fort Lookout, Nebraska ". Another error 

 occurred in the original notice of the species, the name being printed 

 muUistriata for multistrata, iu allusion to the number of rows of scales. 



Bascanium plaviventre. {B. & Q.) 

 Yellow bellied Black Snake. 



Coluber flavlventris. Say, Long's Exped. R. Mts. ii. 1823, 185. 



Bascanion flaviventris, Bd. & GiR. Cat. N. A. Reptiles, 1853, 96.— Bd. U. S. Mex. B. Surv. 

 ii. pt. ii. 1859, Reptiles, 20.— Hayd. Trans. Amer. Phil. Soc. xii. 1862, 177.— 

 Allen, Proc. Bost. Soc. N. H. xvii. 1874, 69 (Yellowstone). 



This species is dark olive-green above and bright yellow beneath, 

 being distinguished from the usual style of B. constrictor by these char- 

 acters, the last-named species being lustrous pitch-black above and 

 ordinarily greenish-black below. These characters, however, are not 

 diagnostic, as more or less yellow-bellied Eastern constrictor often occurs. 



Inasmuch as individuals of B. constrictor, which have not attained 

 their adult state, resemble greatly in coloration B. vetustum, color cannot 

 be relied upon as a specific point in diagnosis. The position of certain of 

 the upper labial and their relation to the eye and that of the lower 

 postorbital afford the most reliable means of distinguishing the species. 

 In Bascanium constrictor, a line drawn slightly obliquely backward from 

 the junction of the third and fourth upper labials will pass directly 

 through the centre of the pupil of the eye. The same line drawn in B. 

 vetustum, would pass slightly anterior to the centre of the pupil, and in 

 the latter species the lower postorbital lies in a notch between the fourth 

 and fifth upper labials. In B. constrictor, the lower postorbital rests on 

 the upper border of the fourth upper labial. In some cases, the position 

 of the lower postorbital in B. vetustum differs on difl:erent sides of the 

 same individual. The young of B. vetustum can hardly be distinguished 

 from the young of B. constrictor except by the position of the lower 

 postorbital. The description of the young by Baird and Girard, p. 94 of 

 their Catalogue, i/? excellent, and should be relied upon, as young speci- 

 mens differ so materially in coloration from adults. 



