54 COLUBRID. 
Scales in 21 rows; ventrals 236; subcaudals 
70; head with a lyre-shaped pattern ; 
dorsal spots im pairs .........e.eee eens 3. lyrophanes, p. 56. 
II. Six or seven upper labials ; scales in 23 rows. 
4. tau, p. 56. 
1. Trimorphodon biscutatus. 
Dipas biscutata, Dum. § Bibr. vii. p. 1153 (1854). 
Dipsadomorphus biscutatus, Giinth. Cat. p. 176 (1858). 
Trimorphodon biscutatus, Cope, Proc, Ac, Philad. 1861, p. 297, and 
Proc. Amer. Philos. Soc. xi. 1869, p. 152 ; és, La Naturaleza, 
vi. 1882, p. 145, fig. ; Cope, Proc. Amer. Philos. Soc, xxiii, 1886, 
p. 286; Giinth. Biol. C.-Amer., Rept. p. 174 (1895). 
Eteirodipsas biscutata, Jan, Elenco, p. 105 (1863). . 
Timorhodon major, Cope, Proc, Amer. Philos. Soc. xi. 1869, p. 153. 
Sibon biscutatum, part., Garm. N. Amer. Rept. p. 16 (1883). 
P arcade lambda, Cope, Proc. Amer. Philos. Soc. xxiii. 1886, 
p- 286. 
Rostral broader than deep, the portion visible from above measur- 
ing one fourth to one half its distance from the frontal; internasals 
much shorter than the prefrontals, which are usually broader than 
long; frontal once and one fourth to once and a half as long as 
broad, as long as or a little longer than its distance from the end of 
the snout, as long as or slightly shorter than the parietals ; two or 
three loreals, rarely one ; two (rarely one) preeoculars, usually with 
a subocular below ; the upper preocular in contact with or narrowly 
separated from the frontal; three postoculars; temporals small, 
scale-like, 2+3, 3+3, or 3+4; nine (rarely eight) upper labials, 
fourth and fifth (in one specimen third, fourth, and fifth, owing 
to the absence of subocular) entering the eye; four or five lower 
labials in contact with the anterior chin-shields, which are longer 
than the posterior. Scales in 23 to 27 rows, usually 25. Ventrals 
234-264; anal divided; subcaudals 74-94. Pale greyish or 
brownish above, with dark, black-edged cross-bars or transverse 
markings with light centre; head with angular dark bands sepa- 
rated by a crescentic transverse light area between the eyes and a 
A- or A-shaped one on the occiput ; lower parts whitish, more or 
less mottled with brown, with large dark brown spots on the sides. 
Total length 1200 millim. ; tail 230. 
Mexico to Panama. 
a. - i 25; V. 261; Mazatlan. Hr, A. Forrer (C.}, 
8 
b-d, e-g. 3 (Sc. 25, 25, Presidio. Hr, A. Forrer (C0. ]. 
24; V. 250, 249, 243 ; 
C. 85, 84, 87), 2 (Se. 
25; V.255; 0.78), & 
yg. (Sc. 25, 23; V. 
h. Her 8 (Se. 25; ¥ Oax M. Sallé [C.] 
‘ . 2 (Se. 26; YV. aca, . Sallé [C. |. 
958; O. 74). 
