i8 Field Columbian Museum 



This species is quite different from Crotalus atrox B & G, which 

 it most resembles, in being much darker, in the indistinctness of the 

 dorsal blotches, the dark mottled ventral surface, and in having a 

 black tail crossed with light bands; the stripes on the side of the 

 head are quite different. Named for Mr. Edmund Heller, its dis- 

 coverer. 



Crotalus cerastes Hallowell. Horned Rattlesnake: Sidewinder. 



"This species is rather common in the Colorado and Mojave 

 deserts, but owing to its strictly nocturnal habits individuals are 

 seldom seen. Many tracks were seen on the sand dunes in the Mes- 

 quite Valley, but only two individuals were seen, both of which were 

 captured. The sidewinder is common in northeastern Lower Cali- 

 fornia, where it is confined to low gulf strip." 



Specimens of this species were secured at the following localities: 

 Mesquite Valley, California,— scales 21-150-21 ; length of body 457mm. ; 

 tail, 38.1mm., — scales 21-142-25; length of body 330mm. ; tail 38.1mm 

 Ballarat, California, — scales 21-148-18; length of body 417mm. ; tail 

 44.5mm., — scales 23-140-24; length of body 238mm.; tail 25.4mm. 

 Daggett, California, — scales 21-141-25; length of body 266mm.; tail 

 30.6mm. Oro Grande, California, — scales 23-143-17; length of body 

 404mm. ; tail 27.9mm. San Felipe, Lower California, — scales 23-148-19 ; 

 length of body 592mm.; tail 38.1mm. 



Crotalus mitchellii (Cope). Bleached Rattlesnake. 



Two specimens of this species were secured in Lower California, 

 where it appears to be not very common. The smaller one has ten 

 rattles, the larger six. 



Parral, Lower California, — scales 25-174-25; length of body 

 744mm. ; tail 60.9mm. San Matias, Lower California, — scales 

 25-177-24; length of body 970mm.; tail 60.9mm. 



Crotalus willardi sp. nov. Plate IIL 



One specimen, No. 902, from Tombstone, Arizona. Scales 

 25-160-24, length of body 380mm.; tail 35mm.; head flat, the 

 snout slightly elevated ; rostral higher than wide in contact with the 

 prena.sals; scales on top of head small, the anterior ones slightly 

 enlarged, and with their anterior edges elevated; preocular large, not 

 divided vertically; scales in front of supraocular small; loreal single; 

 supra labials 14; inferior labials 13; two rows of scales between 

 supralabiaN -m-l "ve; eight rows of scales between stipraocular plates; 



