74 BOIDE. 
2. Seales smooth or unicarinate. 
Head covered with small scales ; rostral large. 
18. Eryx, p. 122. 
Head covered with small scales; rostral moderate, deeper than 
to Pee ee tek re Oe 19. Lichanura, p. 129. 
Head covered with large shields ; rostral large. 
20. Charina, p. 130. 
Subfam. 1. PYTHONINZ.. 
Pythonina, Gray, Zool. Miscell. p. 48, 1842. 
aodoniens (Pythonides), Duméril § Bibron, Erp. Gén. vi. p. 381, 
Pythonina, Gray, Cat. Sn. p. 82, 1849. 
Pythones, Loxocemi, Cope, Proc. Ac. Philad. 1861, p. 304. 
Erycides, part., icine Jan, Icon, Gén. Ophid. p. 64, 1864. 
Loxocemina, Pythonina, Chondropythonina, Boulenger, Bull. Soe. 
Zool. France, 1879, p. 147. 
a ca Chondropythoninez, Boulenger, Faun. Ind., Rept. p. 244, 
90. 
Supraorbital bone present. 
1. LOXOCEMUS. 
Loxocemus, Cope, Proc. Ac. Philad. 1861, pp.76 & 304; Bocourt, 
Miss. Se. Mex., Rept. p. 514 (1882). 
Plastoseryx, Jan, Arch. f. Nat. 1862, p. 242, and Icon. Gén. p. 65. 
(1864). 
Premaxillary bone toothed. Anterior maxillary and mandibular 
teeth longest, gradually decreasing in size. Head not distinct 
from neck, covered with symmetrical shields; rostral large and 
projecting; no loreal shield, preefrontals in contact with labials ; 
nostrils lateral, in a small nasal, which is separated from its fellow 
by a pair of internasals; frontal in contact with an azygous 
occipital shield. Eye small, with vertical pupil. Body cylin- 
drical; scales moderate, smooth. Tail short, conical, not prehensile; 
subcaudals in two rows. 
Mexico. 
1. Loxocemus bicolor. 
Loxocemus bicolor, Cope, Proc. Ac. Philad, 1861, p. 76; Giinth. 
Ann. § Mag. N. H. (3) ix. 1862, p. 55, and Zool. Rec, 1864, 
Peace Bocourt, Miss. Sc. Mex., Rept. p. 515, pl. xxx. fig. 5 
(1882). 
Plastoseryx bronni, Jan, Arch. f. Nat. 1862, p. 244, and Icon. Gén. 
p. 66, 1. 3, pl. i. (1864), Pye 
Loxocemus sumichrasti, Bocourt, Journ. de Zool. vy. 1876, p. 344. 
—— bronni, Bocourt, Miss. Sc. Mex., Rept. p. 516, pl. xxx. fig. 6. 
Snout very prominent. Rostral broader than deep, the portion 
