HOMALOCRANIUM, 153 
inferior rostral. Scales in fifteen rows, last one slightly larger.  Ventrals 148; caudals 
67 pairs.. Total length 10 inches 3 lines; tail 3 inches. — 
“Colour above chestnut-brown, much darker posteriorly, extending upon the tips of 
the ventrals. Anteriorly the scales are edged with darker, presenting a reticulated 
appearance. Central dorsal row of scales lighter, forming a pale vitta, disappearing on 
the tail. Third and fourth rows on each side also lighter, forming indistinct bands. A 
collar of the same pale yellow-brown crosses the ends of the occipitals, Cephalic plates 
clouded and edged with darker; a deep brown mark extending from the occipitals to 
the mouth across.the yellowish labials. Beneath pale yellow, deepening posteriorly.” 
16. Homalocranium canulum. 
Tantilla vermiformis, Cope, Proc. Ac. N. Sc. Phil. 1867, p. 126 (nec Hallowell). 
Lanitilla canula, Cope, Journ. Ac. N. Sec. Phil. viii. p- 144 (1876); Proc. U.S. Nat. Mus. xiv. 
p. 598 (1892). 
Hab. Mexico, Yucatan (Schott). 
Anterior and posterior frontals narrow, transverse; vertical small, longer than suture 
to rostral, angular in front. Supraoculars rather large ; occipitals longer than vertical. 
Seven upper labials; posterior nasal in contact with the preeocular ; two postoculars. 
Temporals 1+1. The first pair of lower labials are separated from each other. Scales 
in fifteen rows. Ventrals 110; subcaudals 37. Lead-coloured, darker above. 
17. Homalocranium mexicanum. 
Elapomorphus mexicanus, Giinth. Ann. & Mag. N. H. 1862, ix. p. 57, t. 9. fig. 1. 
Hab. Mexico (Sallé). 
Nasal simple. Head flat, depressed, short; eye small, but rather more than half as 
long as the snout. Anterior frontals broad, but very short, their longitudinal diameter 
being only one-fourth of that of the posterior; vertical six-sided, of moderate length ; 
occipitals not much longer than vertical. Posterior frontal in contact with the second 
labial; one anterior ocular, not reaching to the upper surface of the head; two post- 
oculars. Seven upper labials, the third and fourth of which enter the orbit, the seventh 
being the largest. A rather large temporal shield in contact with the postoculars; a 
small one behind between the seventh labial and the occipital. The median lower 
labial is exceedingly small; the first pair of lower labials are narrow, transverse, and 
form a suture together; two pairs of chin-shields, of nearly equal size. Scales in 
fifteen rows, without apical groove. Ventral shields 158; anal bifid; subcaudals 52. 
Brownish-olive, with three blackish longitudinal bands, viz. one, almost linear, along 
the vertebral series of scales; the two others along the sides, each composed of two 
blackish lines—one line running along the middle of the second outer series, the other 
_ BIOL. CENTR.-AMER., Rept., January 1895. | | *20 | 
