628 



NORTH AMERICAN SNAKES — COPE. 



above by a black Hue from the orbit to tbe ueck. The muzzle of this 

 speciuien is broken oft. 



This species presents the interesting peculiarity of resembling another 

 species {B. jimielUforme) much more in the adult than in the young stage. 

 The young of the two species refer them to different sections of the 

 genus, while the adults are distinguishable only on careful examination. 



Bascanhim scmiJinratiim Cope. 



Bascanmm laterale Hallow. 



Bascanium twniatum laferaie Cope, Check List Batr. Eept. N. Amer., 1875, p. 40 ; Lep- 

 fophis lateralis Hallowell, Proc, Acad. Pbila., 1853, p. 237; U. S. Pac. R. R. Re- 

 port, X, 1859 ; Williamson's Report, p. 13, PI. iv, Fig. 3. 



This handsome species has two strongly marked subspecies, which 

 may prove to be deserving of the rank of two species. The decision of 

 this question must depend on future material. 



The range is southern California and Arizona to the extremity of 

 Lower California. 



The subspecies are as follows : 



Lateral stripe contiuuous to origin of tail ; throat and upper and lower labials spotted ; 

 posterior upper labials less elongate ...B.l. laterale. 



Lateral stripe broken up on anterior fourth of length, after which a trace only re- 

 mains ; labial plates and throat unspotted ; posterior lateral plates more elongate. 



B. I. aurigulum. 



Bascanium laterale laterale Hallow. 

 Leptophis ?atera?i8 Hallowell, 1. c. Ilascanium taniatum laterale Cope, 1. c. 



The seventeen rows of scales, together with the coloration, distin- 

 guish this form from the B, schottii and the B. twniatum. Young S})eci- 

 mens of the latter, however, resemble it closely, since the spaces be- 

 tween the dark lines of the first, second, and third rows are apt to be 

 solidly dark-colored at that age. They may be distinguished, apart 

 from the smaller number (15) of scale rows, by the different distribution 

 of the lateral stripes. In B. I. laterale the yellow stripe extends to the 

 fifth row of scales, and the inferior band only reaches to the middle of 

 the first row, not attaining the gastrosteges. In B. schottii the supe- 

 rior lateral stripe is as in jB. /. laterale, but the belly is dark, and there 

 is a yellow stripe on the adjacent edges of the gastrosteges and first 

 row of scales. The head is unicolor, and not spotted as in the B. I. lat- 

 erale. The yellow temporal spot of both forms of the B. laterale is to 

 be noted as always absent from the allied species. The B. semiUneatum 

 agrees with the />. laterale in the possession of seventeen rows of scales, 

 and the young is more fully striped than the adult. It may be distiu- 



