458 AMBLYCEPHALIDE. 
16. Leptognathus articulata. 
Dipsas brevis (non D. §& B.), Cope, Proc. Ac. Philad. 1860, p. 266 
a, ang hus articulata, Cope, Proc. Ac. Philad. 1868, pp. 107 ‘& 
Body very slender, strongly compressed. Eye large. Loreal 
bordering the eye; no preocular ; prefrontal entering the eye; two 
postoculars ; temporals 243; nine upper labials, fourth and fifth 
entering the eye; first lower labial in contact with its fellow 
behind the symphysial; four pairs of chin-shields. Scales in 
15 rows, vertebrals enlarged. Ventrals 215; anal entire; sub- 
caudals 135. Yellow, with broad brown entire annuli, which are 
wider anteriorly than posteriorly, and wider than the interspaces 
between them; top of head, sides, and upper labials in front of 
the eye, and all the lower labials, brown; rest of head with 
numerous short lines on the snout, yellow or white. 
Total length 675 millim, ; tail 225. 
Costa Rica. 
17. Leptognathus incerta. 
Leptognathus incertus, Jan, Elenco, p. 101 (1863), and Icon. Gén. 
7, pl. vi. fig. 1 (1870), 
Body slender, strongly compressed. Eye large. Rostral broader 
than deep, scarcely visible from above ; internasals two thirds the 
length of the prefrontals; frontal slightly longer than broad, as 
long as its distance from the end of the snout, shorter than the 
parietals; nasal entire; loreal slightly deeper than long, bordering 
the eye; a prewocular above the loreal; two postoculars ; temporals 1, 
2, or 3+-2 or 3; nine upper labials, fourth, fifth, and sixth entering 
the eye; first lower labial in contact with the symphysial; three 
pairs of chin-shields, anterior a little longer than broad. Scales in 
15 rows, vertebrals moderately enlarged. Ventrals 204; anal 
entire; subcaudals 122. Pale brown above, with large dark brown, 
black-edged cross-bars or alternating spots; a dark brown spot on 
each parietal shield; pale brown beneath, with interrupted darker 
streaks. 
Total length 720 millim. ; tail 220. 
Guianas, Brazil. 
a. 3 (V. 204; C. 122). 8. José dos Campos, Prov. Mr. A. Thomson 
S. Paulo, Brazil. [P.]. 
18. Leptognathus argus. 
Leptognathus argus, Cope, Journ. Ac, Philad, (2) viii. 1876, p. 180, 
Rostral very small, triangular, as deep as broad; loreal and 
prefrontal bordering the eye in front; two postoculars; temporals 
1+2; seven upper labials, fourth, fifth, and sixth entering the 
eye; three pairs of chin-shields, anterior longer than broad and in 
contact with the symphysial. Scales in 15 rows, vertebrals not 
