62 



BULLETIN 61, UNITED STATES NATIONAL MUSEUM. 



date and locality. There are, however, two specimens from San Ilde- 

 fonso (8416-8417) of eques that are labeled marcianus, while it is to 

 be noted that the only specimens from Taos in the Museum are 

 elegans. 



With these gross errors confronting us in the literature, it is evi- 

 dent that we can trust neither the general ranges given nor the detailed 

 locality records. I may be excused, therefore, for confining my 

 discussion of the range of this group principally to the specimens 

 that I have examined. Fortunately the doubtful localities are 

 rare, for I have examined the specimens upon which most of the 

 records have been based. I have examined specimens with defi- 



FiG. 22.— Distribution of Thamnophis marcianus, as indicated by the locality records. 



nite locality records as follows: Fort Yuma, California; White Horse 

 Springs, and Fort Supply, Oklahoma; Matamoras and Charco Escon- 

 dido, Tamaulipas, and Ojo del Diable, Chihuahua, Mexico; Browns- 

 ville, San Diego, Point Isabelle, Reutersville, Cameron County, San 

 Antonio, Indianola, Eagle Pass, Pecos, San Angelo, Helotes, Jeff Davis 

 County, "South of Clarendon," Kerrville, Texas; Tucson, Arizona; 

 ''Red River, Arkansas. " 



When these localities are plotted on a map (fig. 22) the distribution of 

 the form is seen to be more extensive than has been generally stated. 

 In the Proplateau region it is known from as far west as Yuma, 



