restricted to Tehuantepec, Oaxaca, Mexico, by Smith and
Taylor (1950a:340).

_Trimorphodon biscutatus biscutatus_, Smith, Proc. U. S.
Natl. Mus., 91:159, November 10, 1941.

Apatzingan (11); Cofradia; Cuatro Caminos; El Sabino (2); La
Placita; La Playa (2); Lombardia (2); Nueva Italia (2); Rio
Tepalcatepec, 27 km. S of Apatzingan; Tafetan.

In the arid lowlands of the Tepalcatepec Valley and presumably also in
the scrub forest of the coastal lowlands, this is an abundant snake,
which is active only at night. Usually snakes of this species are found
on the ground, but one large individual was observed at night in a low
tree. That individual defied capture by widely opening its mouth and
striking repeatedly at the collector. The excreta of one specimen
contained feathers of an unidentified species of bird.

~Trimorphodon latifascia~ Peters

_Trimorphodon biscutata latifascia_ Peters, Monats. Akad.
Wiss. Berlin, p. 877, 1869.--Puebla, Mexico. Type locality
restricted to Izucar de Matamoros, Puebla, Mexico, by Smith
and Taylor (1950a:341).

_Trimorphodon latifascia_. Taylor, Univ. Kansas Sci. Bull.,
25:364, July 10, 1939.

Apatzingan (5); Casada Tzararacua; Coalcoman (2); Lombardia;
14 km. S of Lombardia; Nueva Italia; San Salvador.

In Michoacan this species has been collected in semi-arid habitats at
elevations from 300 to 1430 meters in the Tepalcatepec Valley and lower
slopes of the Cordillera Volcanica. In this area it occurs sympatrically
with _Trimorphodon biscutatus biscutatus_.

In life, adults have a pale tan dorsal ground color and rich chocolate
brown cross-bands; the eye is pale grayish tan. A juvenile from
Coalcoman has black cross-bands on a pale grayish tan ground color. As
stated by Schmidt and Shannon (1947:83) and Peters (1954:32), the type
specimen of _Trimorphodon fasciolata_ Smith from Cascada Tzararacua is
indistinguishable from specimens of _Trimorphodon latifascia_.

Seven males have 209 to 223 (216.5) ventrals; one female has 227
ventrals. The number of dark cross-bands on the body varies from 12 to
16 (13.5). The relationships of this species are with _Trimorphodon
tau_ on the Mexican Plateau. In fact, additional specimens from the
headwaters of the Tepalcatepec Valley and the lower slopes of the
Mexican Plateau in eastern Michoacan and adjacent Jalisco may show that
the two are conspecific. _Trimorphodon latifas