686 Bulletin American Museum of Natural History [Vol. XLVI 



to the keeling of the scales on the posterior part of the body in the latter 

 species. Stejneger, in the original description (loc. cit., p. 153) distin- 

 guished P. browni by the following characters: 



P. decurtatus P. browni 



Posterior Dorsal Scales Smooth Keeled 



Ventral Plates 172-177 159 



Subcaudals 26-27 31 



Tail-Length .08-. 09 .13 



Lateral Spots Present Absent 



Dorsal Spots • 29-32 15 



The specimen recorded from La Paz by Van Denburgh and Slevin 

 (1921a, p. 66) has 161 ventrals and 35 subcaudals, thus agreeing with the 

 scale counts of P. browni. Mr. Tracy I. Storer of the Museum of Verte- 

 brate Zoology of the University of California has kindly examined the 

 specimen recorded from Palm Springs, Riverside Co., California, by 

 Atsatt (1921, p. 38) and informs me that it has 187 ventral plates and 32 

 subcaudals. 



A specimen (A. M. N. H. No. 20590) collected by Dr. F. E. Lutz 

 and J. A. G. Rehn near Tucson agrees with browni in every scale char- 

 acter, but has the dorsal coloration of decurtatus while a second specimen 

 from the same locality is a typical browni. This extraordinary dimorph- 

 ism in coloration can only be explained by further studies, depending on 

 the discovery of additional specimens. My suspicion that the differences 

 in scale counts alluded to is a sex character is apparently groundless, as 

 Dr. Stejneger reports U. S. N. M. No. 62561, a browni, as a female, and 

 the specimen from Palm Springs is reported to be a male by Mr. Storer. 

 I append a tabulation of the characters of the extant specimens of these 

 two species so far as I can determine them. 



Elaphe rosalise (Mocquard) 

 Coluber rosalise Mocquard, 1899, p. 321, PI. xn, fig. 1. 

 Elaphe rosalise Stejneger and Barbour, 1917, p. 84. 



Range. — Central and southern Lower California. 



Lower Californian Records. — Santa Rosalia, Mocquard, 1899, p. 321; San 

 Bartolo, Van Denburgh and Slevin, 1921a, p. 66. 



Arizona elegans Kennicott 

 Arizona elegans Kennicott, 1859, p. 18, PI. xm; Stejneger and Barbour, 1917, 



p. 85. 



Range. — Southwestern United States, northern Mexico, northern Lower Cali- 

 fornia. 



Lower Californian Records. — Ensenada, Van Denburgh and Slevin, 1921a, 

 p. 67. 



