13. cROTALUS. 573 
Three to ten series of scales between the 
supraoculars, which are in contact with 
six to eleven scales in addition to the pre- 
and postocwiars: 7... cs ae marie ee ers 3. confluentus, p.576. 
3. Supraocular shields smooth, much narrower than the 
space between them. 
Two pairs of internasals; rostral deeper than 
WS a ae < 6-34 ary Ske eh cio 4, durissus, p. 578. 
One pair of internasals ; rostral as deep as 
DROS oo oc GMaREs © 0 ia isle Beek ths qe nas 5. horridus, p. 578. 
2. Rostral broader than deep, in contact with the nasal ; 
scales in 23 or 25 rows; ventrals 166-181. 
6. tigris, p. 580. 
3. Rostral broader than deep, separated from the nasal by 
scales; scales in 25 rows; ventrals 178-198. 
7. mitchelli, p. 580. 
B. Eye separated from the labials by one or two rows of scales. 
1. Upper preocular normal, separated from the nasal by a 
loreal; rostral as deep as broad, 
Two internasals; scales in 21-25 rows; 
Ventas 142-184 oa cyigislere dine vinls e's sin 8. triseriatus, p. 581, 
Four internasals; scales in 27- 30 TOWS; 
VOROS POLO. fa cesis ie aew elieiones 9. polystictus, p. 582. 
2. Upper preocular divided into two by a vertical suture; 
rostral broader than deep ; scales in 21—23 rows ; ventrals 
POOF SOM eer ke ahe ses pases 10. lepidus, p. 582, 
II. Supraocular produced into a horn-like process: scales in 21 or 
23 rows; ventrals 146 ........... . Ll. cerastes, p. 583. 
1. Crotalus terrificus. 
» Seba, Thes. ii. pl. xcv. figs. 1 & 2, & pl. xevi. fig. 1 (1735), 
? Crotalus dryinas, Linn. “Ss. WV. i. p- 872 (1766). 
Ca rrifica, Laur. Syn. Rept. p. 93 (1768) ; Cope, Proc. Ac. 
i 6, p. 308. 
? Caudiso dryinas, Laur, l. ¢. p. 94. 
Caudisona orientalis, Laur. 1. e. 
Crotalus boiquira, part., Lgety. Serp. ii. pp. 180, 190 (1789), 
durissus, var., Shaw, Zool. iii. pl. xc. (1 802). 
horridus (non L.), Latr. Rept. iii. p. 186 (1802) ; Daud. Rept. 
v. p. 31], pl. lxix. fig. 1 (1803) ; Harl. Proc. Ae. Philad. v. 1827, 
p. 370; Wied, Abbild. Nat. Bras. (1827); Schleg. Phys. Serp. ii. 
Pp. 561, pl. xx. figs. 12-14 (1837); Dum. §& Buibr. vii. p. 1472, 
pl. Ixxxiv. 0. fig. 2 (1854) ; Hensel, Arch. f. Nat. 1868, p. 338; 
Jan, Icon, Gén. 46, pl. iii. figs. 1& 2 (1874); Peracca, Boll. Mus. 
Torino, x. no, 195, 1895, p. 22. 
cascavella Wagl. in Spix, Serp. Bras. p. 61, pl. xxiv. 
(1824), : 
