520 VIPERIDZ. 
from the labials by suboculars ; scales 
in 23 (rarely 25) rows; ventrals 
135-141 ; subcaudals 52-64........ 2. bilineatus, p. 521. 
A loreal, usually separating the upper 
preocular from the posterior nasal ; 
eye separated from the labials by 
suboculars; scales in 23 (rarely 25) 
rows ; ventrals 145-155; subcaudals 
BL -~BB. Vsisaivetengaee su vig-erts se hee 3. contortrix, p. 522. 
b. Snout ending in a pointed appendage; scales in 21 rows; 
ventrals 162-166 ; subcaudals 58-60. 
4. acutus, p. 524. 
2. Subcaudals all paired ; loreal pit separated from the labials ; 
we ventrals 137-174; subcaudals 31-55. 
a. Posterior labials distinct from the temporals, 
Snout slightly turned up at the end;- 
scales in 2B TOWS ....60 65s see oes’ 5. halys, p. 524, 
Snout not turned up; scales in 23 . 
(rarely 21) TOWS | -... vei 2» 03 06 is 6. intermedius, p. 525. 
Snout not turned up; scales in 21 
(rarely 28) :r0W8 «s\00iss 5050 bowie ee 7. blomhoffii, p. 525. 
b. Posterior labials fused with the temporals ; snout slightly 
turned up; scales in 21 (rarely 23) rows. 
8. himalayanus, p. 526. 
B. Scales smooth, in 21 rows; ventrals 138-157; subcaudals 
34-64 pats... vac eannb ean 9. rhodostoma, p. 527. 
II. Scales in 17 rows, more or less distinctly keeled; snout 
strongly turned up, covered above with small shields ; ventrals 
125-155 ; subcaudals 28-45 pairs. 10. hypnale, p. 528. 
1. Ancistrodon eee 
Crotalus piscivorus, part., Lacép. Serp 180, 424 (1789), 
Scytale pi dua (1808) part, Latr, Kept. AA p- EBs (1802) ; ; Daud. Rept. 
Coluber aquaticus, part., Shaw, Zool. iii. p. 425 (1802). 
Acontias leucostoma, Troost, Ann. Lye, ey . lil, 1836, p. 176. 
Trigonocephalus cenchris, art., Schleg. Phy 8. Serp ii. Dp. 553 (1837). 
—— piscivorus, Holbr. . Am. Herp. ii. p. 68, pl. xiii, (1838), 
and 2nd ed. iii. p. 33, A hh (1842)> Dun. § Bibr. vii. p. 1491, 
. Ixxxii. b. fig. 2 (18654) ; ~ Leon. Gén, 46, pl. iv. (1874) ; 
ocourt, Miss. Sc. Mex., Rept. pl. xxvii, (1882). 
irri piscivorus, Gray, Boa call p. 51 (1842), and Cat. p. 16 
Toxico coh sad Baird & Gir, Cat. N. Am. Rept. p. 19 (1858), 
and lor. Surv. R. R. x, Rept. pl. xxv. fg. 13 (1859), 
pu ard § Gir, Ul. ce. p, 20, fi foe and Rep. US, Mex. 
Bou ‘Beve. ii., x. Rept. p. 15, pl. vi. (1868), 
