OPBIDIA— CROTALIDAE— CKOTALUS SCUTULATUS. 533 



" aa. Rattle parallelogrammic : 



" C.molossus, BairdandGirard. — 2 9 rows of scales; 18 labials, 

 separated by 5 rows from orbit: brownish sulphur above, with 

 small, transverse, reddish, dorsal rhombs, the angles produced 

 as lateral bands ; no longitudinal bands on neck ; tail black. — 

 Arizona and New Mexico. 

 " II. Nasal plates distinct ; muzzle ivith small plates or numerous scales above : 

 "a. Muzzle with 2 marginal shields above each canthus rostralis : 

 u b. An elevated, narrow, cuneiform rostral:* 



" C. pohjstictus, Cope. — Scales 27 rows; superior labials 14, 

 separated from orbit by 2 rows : gray-brown, with 7 longitudinal 

 rows of brown spots ; top of head variegated. — Mexico. 



"0. triseriatus, Wagler. — Scales 23 rows; 2 pairs of large 

 scales on top of muzzle ; 6 rows between orbits : yellowish, with 

 a dorsal series of subround brown spots. — Mexico. 



u C.confluentus,$ny. — Scales 25-7 1 ( — 9) rows; labials 15 

 to 18, separated from orbit by 4 rows; 6 to 10 rows between 

 superciliaries : yellow line from superciliaries above angle of 

 mouth ; a median dorsal row of brown spots, emarginate before 

 and behind, with alternating lateral series. — Central and South- 

 west North America. 



" C. lucifer, Baird and Girard.— Scales 25-7; labials 15- 

 16, with 4 rows above them : numerous subround, blackish, 

 dorsal spots, separated by narrow yellow lines ; a light band 

 from supercilia above angle of mouth. — Pacific Region of North 

 America, Arizona. 



" C. scukdatus, Kennicott. — Scales 25 rows; superior labials 

 16; 3 or 4 rows mterorbital scales, bounded in front by .two 

 shields : yellow stripe from eyebrow above rictus oris : yellowish 

 brown, with a dorsal series of truncate, brown, yellow edged 

 rhombs ; tail black ringed. — Arizona. 



"Note. — Mr. Henshaw informs me he killed several serpents 



* Professor Cope states that the, former division of the species based on tho acumiuate or parallelo- 

 grammic form of the rattle must he abandoned, as several of them with acuminate rattle exhibit a 

 parallelogrammic one when they reach a large size. 



