VARIATIONS OF GARTER-SNAKES. 63 



Arizona, but, as has been elsewhere stated (Iluthven, 1907, 589), 

 since only three '^ specimens have been recorded from here and this is 

 the only record for the Sonoran desert region in Arizona, they should 

 not be taken as establishing the occurrence of the form so far to the 

 westward, for the locality may not be an exact one. Its northern and 

 southern limits in this State can only be conjectured. The single 

 specimen in the U. S. National Museum labeled " Ojo del 

 Diable, Chihuahua," is the southernmost record for the Proplateau 

 region. Aside from the Yuma records, which consist of one specimen 

 in the Academy of Natural Sciences of Philadelphia and two in the 

 U. S. National Museum, all collected by Major Thomas, no other 

 specimens are known to me from southern Arizona, except three in 

 the Academy of Natural Sciences of Philadelphia, two in the National 

 Museum, and one in the American Museum, all from Tucson. It is 

 probable, however, that it ranges north to the Colorado plateau, 

 although no specimens have been taken at Fort Whipple, where con- 

 siderable collecting has been done. It is highly probable that it does 

 not range north of this point. 



For New Mexico there are no authentic records. As we have seen 

 above, Yarrow's specimens are to be referred to elegans, eques, and 

 radix. Cope (1883, 12) records a specimen taken by Frank Snow at 

 Socorro, but I have been unable to verify this record. Without doubt 

 marcianus occurs in the southern part of this State, but its northern 

 limit is a debatable point, for although the high plateau, as in Arizona, 

 may exclude it from all but the extreme southern part, on either side 

 of the Rio Grande, there seems no good reason why it should not occur 

 up the valley of this river at least as far north as Las Cruces. 



In the Trans-Pecos region of Texas marcianus has been recorded 

 from the Davis Mountains, Jeff Davis County, Paisano, and Boquil- 

 las, all localities south of the high plateaus. East of the East Front 

 Ranges the records indicate that it occurs throughout the prairie 

 region of central Texas, and the Rio Grande plain as far south as 

 Charco Escondido, Tamaulipas, north to Fort Supply, Oklahoma, 

 and westward to an undetermineil distance on the plains. Claren- 

 don, Pecos, and San Angelo are the most western records for this 

 region, and it will be noticed that these localities mark approxi- 

 mately the eastern margin of the Staked Plains. Whether this 

 indicates the actual western limit of the form in this region, or the 

 lack of specimens from more western localities, can not of course 

 be determined. As in the Proplateau region, however, it is signifi- 

 cant that its chief distribution in Texas is confined to the lower 

 altitudes, so that it would not be surprising to find that its w^estern 

 range is limited by the increasing altitude of the high plateau, the 

 Pecos records possibly indicating that it j)ushes to some extent up 



a Erroneously given as two in the pai)er mentioned. 



