12. sisrrurvs. 569 
imbricate, large, shield-like and smooth or feebly keeled on the 
snout and vertex; an enlarged frontal, separated from the large 
supraocular by a series of two or three smaller shields; internasals 
small ; two postoculars and a subocular, separated from the labials” 
by one series of scales; temporal scales keeled; 9 or 10 upper 
labials, second forming the anterior border of the loreal pit. Scales 
rather strongly keeled, in 19 rows. Ventrals 154-158; anal entire; 
subcaudals 53-61, single. Tail prehensile. Green above, with 
more or less distinct, scattered yellow spots ; a more or less distinct 
black streak on the temple ; greenish yellow beneath. 
Total length 825 millim. ; tail 145. 
Guatemala. 
a. Q (V. 154; C, 53), Coban, Vera Paz. O. Salvin, Esq. [C.]. 
/(Type.) 
b. g (V. 158; C. 61). Coban. O. Salvin, Esq. [C.]. 
12, SISTRURUS. 
Crotalus, dss Linn, 8. N. i. p. 872 (1766) ; Schleg. Phys. Serp. ii. 
p- 555 (1837) ; Dum. § Bibr. Erp. Gén. vii. p. 1458 (1854) ; Jan, 
Caen sist. Ofid. p. 125 (1863). 
Crotalophorus (non Houtt.), Gray, Ann. Philos, 1825, p. 205, and 
Cat. Sn. p. 17 (1849); Cope, Proc. U.S. Nat. Mus. xiv. 1892, 
p- 684, 
Oaudiacns (non Laur.), Fitzing. N. Class. Rept. p.84 (1826) ; Wagl. 
Syst. Amph. p. 176 (1830) ; Gray, Zool. Miscell. p. 51 (1842), 
Sistrurus, Garm. N. Am. Rept. p- 110 (1883), and Science, xix. 
1892, p. 290; Stejneger, Rep. US. Nat. Mus. f. 1898, p. 410 
(1895) ; W. E. Taylor, Am, Nat. 1895, p. 288. 
Head very distinct from neck, covered above with nine large, 
symmetrical shields; eye moderate or small, with vertical pupil. 
Body cylindrical; scales keeled, with apical pits ; ventrals rounded. 
Tail short, ending in a segmented, horny, sound-producing apparatus 
or rattle ; subcaudals all or greater part single. 
North America East of the Rocky Mountains ; Mexico. 
Synopsis of the Species. 
Rostral as deep as broad or deeper than broad ; 
loreal separating the upper preeocular from 
the posterior nasal ; canthus rostralis sharp. 1. miliarius, p. 569. 
Rostral as deep as broad or deeper than broad ; 
upper preocular in contact withthe posterior 
nasal; canthus rostralis sharp.......... 2. catenatus, p. 570. 
Rostral broader than deep; loreal separating 
the upper preocular from the posterior 
nasal ; canthus rostralis obtuse ........ 3. ravus, p. 571. 
1. Sistrurus miliarius. s 
Crotalus miliarius, Linn. 8S. N. i. p. 372 (1766); Daud. Rept. v. 
p- 828 (1808); Say, Amer. Journ. M50 i. 1819, p. 263 ; Harl. Journ, 
Ac, Philad. y, 1827, p. 371, and Med. Phys. Res. p. 134 (1835) 
