OPHIDIA— CROTALIDAE— APLOASPIS LEPIDA. 535 



as high ; rattle parallel ogrammic ; scales 21-3 ; labials 11- 



13 : light yellowish, with several series small brown spots, 



median largest. — Deserts of the Gila and Colorado, Arizona. 



" Note. — Lieutenant Wheeler informs me that during his boat trip up 



the Colorado in September, 1871, very many serpents presumably of this 



species were seen on the rocky and sandy banks of the river. 



" The Indian guides and porters moved among them apparently fearless 

 of their bite, as at the time they were shedding their skin, and blind. They 

 were also seen in Arizona, and are called ' side-winders ' by the settlers, 

 owing to their peculiar lateral progressive motion. 



11 dd. Premised separated from rostral by scales ; superciliary not pro- 

 longed: 



" C. niitchellii, Cope. — Rostral broad as long; scales 25 rows; 

 labials 16, separated from orbits by 3 rows ; 2 elongate pre- 

 orbitals ; 1 loreal : yellowish-gray, with indistinct quadrate 

 dorsal spots, separated by yellow, and becoming cross bands on 

 posterior fourth ; rattle parallelogrammic, — Lower California, 



"C. pyrrhus, Cope. — Rostral broad as long; head very 

 obtuse, rounded; scales 25 rows, 7 between superciliaries, 3 

 below orbit ; labials 14; 2 very small preorbitals, and 4 loreals: 

 pale vermilion, varied with yellow on the sides of the belly, 

 with numerous large reddish-bay, transverse hexagons, which 

 become transverse bands on posterior two-thirds of length, 

 yellow below ; rattle subacuminate. — Arizona. 

 " The C. lepida of Kennicott is the type of a genus formerly defined 

 under the name of Aploaspsis, and characterized by the 'presence of a single 

 large nasal shield, which is pierced by a small central nostril. 

 "I. Muzzle with numerous smooth plates above : 



"A. lepida, Kennicott. — Rostral broad, low ; scales of top of 

 muzzle and vertex large, smooth ; upper preorbital very small ; 

 loreals 3 ; labials 12, separated by one row from orbit ; no post- 

 ocular band. — Rio Grande, Texas. 



