112. arractus. | 305 
one postocular (exceptionally two); temporals 1+2; six upper 
labials, third and fourth entering the eye; two pairs of chin-shields, 
posterior half as long as anterior. Scales in 17 rows. Ventrals 
172-179; anal entire ; subeaudals 24-82. Uniform dark plumbeous 
above, margins of scales lighter; a yellow occipital bar may be 
present, crossing the parietal shields; ventrals white, mottled with 
leaden, or uniform leaden. 
Total length 455 millim.; tail 45. 
Mexico (San Luis Potosi and Hidalgo). 
6. Atractus longiceps. 
Rhabdosoma longiceps, Cope, Proc. U.S. Nat. Mus. ix. 1886, p. 189. 
Agrees in most respects with <A. latifrontalis, but snout more 
elongate and prefrontals much longer than broad. Ventrals 173 ; 
subeaudals 28. Extremity of tail with a compressed horny cap. 
Colour everywhere blackish; some brownish shades on the sides 
near the head; free edges of ventral and subcaudal shields, and of 
lateral scales, lighter. 
Total length 445 millim. ; tail 44. 
Vera Cruz, Mexico. 
7. Atractus peruvianus. 
Rabdosoma peruvianum, Jan, Arch. Zool. Anat. Phys. ii. 1862, p. 12, 
and Icon. Gén. 10, pl. iv. fig. 2 (1865). 
Snout obtuse. Rostral much broader than deep, just visible from 
above; internasals small; preefrontals. not quite as long as broad ; 
frontal small, as long as broad, as long as the prefrontals, much 
shorter than the parietals; loreal at least twice as long as deep; 
two postoculars: temporals 142; six upper labials, third and 
fourth entering the eye; four lower labials in contact with the 
single pair of chin-shields, which are moderately large and separated 
from the symphysial. Scales in 17 rows. Ventrals 140; anal 
entire ; subcaudals 31. Brown above, with five longitudinal series 
of black spots; ventrals black, with a white spot at the outer end; 
lower surface of tail white, spotted with black. 
Total length 280 millim. ; tail 40. 
Peru. 
8. Atractus guentheri. 
Rhabdosoma maculatum, part., Giinth. Cat. p. 241 (1858). 
Geophis guentheri, Wacherer, Proc. Zool. Soc. 1861, p, 115, pl. xix. 
fig. 1; Giinth. Zool. Rec. 1865, p. 151. 
Rabdosoma univittatum, Jun, Arch. Zool. Anat. Phys. ii. 1862, 
p- 15, and Icon. Gén. 11, pl. ii. fig. 2 (1865). 
Snout rounded. Rostral small, broader than deep, just visible 
from above; internasals very small; preefrontals broader than long; 
frontal a little broader than long (or as long as broad), as long ay 
VoL. Il. E x 
