Vol. VIII] I'A.y DENBURGH AND SLEVIN— GARTER-SNAKES 261 



Thamnophis marcianus (Baird & Girard) 

 Marcy's Garter-Snake. 



Diagnosis. — Nomially with eiglit supralabials ; twenty-one 

 (or more) rows of scales; dorsal line distinct; lateral line an- 

 teriorly on scales of third row only; large, distinct dorsal dark 

 spots and dark nuchal blotches ; light postoral crescents ; pre- 

 ocular single ; infralabials often eleven. 



Type Locality. — Red River, Arkansas=Cache Creek, Okla- 

 homa, according to Ruthven. 



Synonyms. — Eutcenia nigrolatcris Brown, 1889; type local- 

 ity, Tucson, Arizona. 



Range. — This garter-snake seems to occupy territory near 

 the United States and Mexican border from the Gulf of A/Jexico 

 to the Colorado River, extending its range north through 

 Texas to Oklahoma. The details of its distribution through 

 this area are yet to be worked out. As regards Arizona, au- 

 thentic specimens have been recorded from the vicinity of 

 Tucson and Yuma. At Yuma it occurs on both banks of the 

 Colorado River, and the westernmost limits of its known range 

 are along the banks of this river from Yuma north to River- 

 side Mountain in Riverside County. 



We have examined specimens of Thanmopliis marcianus 

 from the following localities : — 



1. Riverside Mountain, Colorado River, Riverside Co., Cali- 

 fornia. 



2. Colorado River, 8 miles east from Picacho, Imperial Co., 

 Cal. 



3. Fairbanks, Cochise Co., Arizona. 



4. Tucson, Pima Co., Ariz. 



5. Yuma, Yuma Co., Ariz. 



Material. — Eight specimens from the above localities in 

 California and Arizona have been studied by us. They, of 

 course, are too few to show the limits of variation. Some data 

 given by Ruthven are added to our own. 



