MESOPELTIS. 143 
MESOPELTIS. 
Mesopeltis, Cope, Proc. Ac. N. Sc. Phil. 1866, p. 318. 
Asthenognathus, Bocourt, Bull. Soc. Philom. viii. p. 141 (1884). 
1. Mesopeltis sanniolus. 
Mesopeltis sanniolus, Cope, Proc. Ac. N. Sc. Phil. 1866, p. 318. 
Hab. Mexico, Yucatan (Schott). 
2. Mesopeltis dimidiatus. (Tab. LI. figg. A, B.) 
Leptognathus dimidiatus, Ginth. Aun. & Mag. N. H. 1872, ix. p. 31. 
Petalognathus multifasciatus, Bocourt, Bull. Soc. Philom. vii. p. 139 (1884). 
Mesopeltis multifasciatus, Cope, Bull. U. S. Nat. Mus. no. 32, p. 67. 
Leptognathus (Asthenognathus) grandoculis, Mill. Verh. naturf. Ges. Basel, viii. p. 271, t. 1. fig. 2 
(1887). 
Hab. Mexico (Mus. Brit.); Guatemata, Vera Paz (Morelet), Mazatenango (Bernoulli) ; 
Nicaragua, Matagalpa 3250 feet (Rothschuh). 
Scales smooth, in fifteen rows, those of the vertebral series not enlarged. Body 
much compressed, neck slender, head broad and short. Eye rather large, with vertical 
pupil. Anterior frontals short and small; posterior frontals large, extending down on 
the sides of the snout, and forming the antero-superior part of the orbit. Vertical 
with nearly parallel outer edges, and with a right angle behind, shorter than the 
occipitals. Loreal confluent with the single preocular; two postoculars. Eight upper 
labials, the fifth and sixth entering the orbit ; (seven upper labials, the fourth, fifth, and 
sixth entering the eye, Miller). Temporals 1+2-+3. Three pairs of chin-shields, the 
anterior the largest, crescent-shaped, much longer than broad; the middle shorter, but 
still longer than broad; the posterior of about the same size as the middle, and 
divergent. An azygos scale-like shield between the front chin-shields and the minute 
median labial. The first pair of lower labials are not joined together by a suture, 
being separated by the azygos shield; the five following lower labials are in contact 
with the anterior chin-shields. Ventrals 186-193; anal entire; subcaudals 98-126. 
Body and tail with broad blackish-brown rings separated by whitish interspaces much 
narrower than the rings; there are twenty-five black rings on the trunk and sixteen on 
the tail. The white interspaces are again each subdivided by a narrow black trans- 
verse line. Upper parts of the head black, with small whitish spots irregularly placed ; 
a pair of large whitish spots on the neck, forming a kind of collar. Anterior chin- 
shields black. In the larger specimen (24 inches) the blackish bands are purplish- 
brown, with broad blackish margins, so broad as to almost entirely occupy the inter- 
spaces, at least on the back; the remainder of each whitish interspace is finely powdered 
with purplish. A black spot on the posterior chin-shields. 
