AGKISTRODON. 17 



Genus AGKISTRODOIV, Beauv. 



Gen. Char. A deep pit between nostril and the eye. Nine 



plates on top of head. Without rattle. Poison fangs as in Crotalus. 



One pair of occipitals. A loral between the nasal and anterior orbit- 



als. Labials excluded from the orbit by the presence of suborbital 



plates. Scales carinated; rows 23 in number. Subcaudal scutellas 



divided posteriorly. Sometimes a small plate between the vertical 



and postfrontals. Habits terrestrial. 



Syn. Aghistrodon, Pal. de Beauv. Trans. Amer. Phil. Soc. Philad. IV, 

 1799, 381. 



1. A^kistrodon contortrix, B. & G. — Loral present. Labials 

 not entering into the orbit. Dorsal rows of scales 23. Color light chestnut, 

 ■with inverted Y "Shaped darker blotches on the sides. Labials yellowish 

 •white. 



Syn. Boa confortrix, Linn. Syst. Nat. I, 273. — Gm. L. Syst. Nat. ed. xiii, 

 I, iii, 1788, 1082, 



Agkistrodon mokason, Be adv. Trans. Amer. Philos. Soc. Philad. IV, 

 1799, 380. 



Scytalus ciipreus, Rafin. Amer. Journ. Sc. I., 85. — Haul. Med. «& Phys. 

 Res. 1835, 130. 



Triffonocephalus cenchris, Sciil. Ess. Phys. Serp. Part, desc, 1837, 653. 

 PL XX, fig. 10 and 11. 



Trigonocephalus contortrix, HotBR. N. Amer. Ilerp. II, 1838, 69 PI. xiv, and 

 2d ed. Ill, 1842, 39. PI. viii. 



Copperhead. . 



More slender than ToxicopMs jnsciovorus. Plates on neck and sido 

 smaller. Two anterior orbitals, one above the other, the lower nar- 

 rower, and forming the posterior wall of the pit. A distinct loral 

 between these and the posterior nasal. Labial not forming part of 

 the orbit, but separated by the four post and suborbitals. Labials 

 not so largely developed ; 8 above, 3d and 4th largest ; 9 below. 



Above light hazel brown, rather brighter on the top of the head, 

 and everywhere minutely mottled with very fine dark points. On 

 each side is a series of 15-26 darker chestnut-colored blotches resting 

 on the abdominal scutellcC, and suddenly contracting about the mid- 

 dle of the side, so as somewhat to resemble an inverted Y- These 



2 



