152 OPHIDIA. 
13. Homalocranium mestum. (Tab. LII. fig. E.) 
Homalocranium mestum, Giinth. Ann. & Mag. N. H. 1863, xii. p. 352. 
Homalocranion mestum, Bocourt, Miss. Sc. Mex., Rept. p. 583, t. 36. figg. 9, 9 a-d. 
Hab. Mexico, Yucatan (Cope); Guatemata, Peten (Salvin). 
Anterior frontals very broad, with the lateral portion produced backwards, about half 
as large as the posterior frontals. Vertical six-sided, much longer than broad, with an 
obtuse angle in front and an acute one behind; occipitals rounded behind, as long as 
the vertical and posterior frontals together ; posterior nasal low, elongate, in contact 
with the single preocular; two postoculars. Upper labials seven, the third and fourth 
entering the orbit, the last being the largest and highest. ‘The median lower labial is 
in contact with the chin-shields, which are twice as long as broad; then follow two or 
three other pairs of small scale-like chin-shields. Scales smooth, in fifteen rows. 
Ventrals 150. Entirely deep black, with a broad yellow collar extending over the hind 
part of the occipitals laterally to the eyes, and below over the whole chin and throat. 
14. Homalocranium schistosum. 
Homalocranion schistosum, Bocourt, Miss. Sc. Mex., Rept. p. 584, t. 36. figg. 10, 10 a-e. 
Hab. Mexico (Boucard); Guaremata (F. D. G. & O. S.), Alta Vera Paz (Bocourt). 
Head very short, flat, and depressed ; eye small, not quite half as long as the snout. 
Vertical shield broad, almost as broad as long, with an obtuse angle in front and a 
slightly acute one behind. Seven upper labials, of which the hindmost is elevated ; | 
posterior nasal in contact with the anteocular ; one ante- and two postoculars ; tem- 
porals 1+1. The first pair of lower labials are widely separated from each other. 
Scales in fifteen rows, without apical groove. Ventrals 135, 121 (Bocourt); subcaudals 
38. Upper parts greyish-brown, with an indistinct narrow lighter collar across the end 
of the occipitals. No white spots on the head. Lower parts white. | 
Our specimen is 84 inches long, of which the tail takes 14. 
15. Homalocranium reticulatum. 
Tantilla reticulata, Cope, Proc. Ac. N. Se. Phil. (1860) 1861, p. 77; Journ. Ac. N. Se. Phil. vii. 
p. 144 (1876). 
Hab. Panama, Cocuyas de Veraguas (Mitchel/). 
This snake, of which I have not seen a specimen, is described as follows :— 
“ Vertical plate broad, slightly angular in front, projecting posteriorly for half its 
length between the occipitals. Occipitals and both pair of frontals rather broad. 
Rostral broad, visible from above. ... . Two postoculars, upper one in contact poste- 
riorly with the occipital, the lower touching one temporal. A second temporal equal 
to the first, and a third very small one behind it. Superior labials seven, last largest, 
third and fourth entering the orbit, both low. Four geneials, anterior in contact with 
