species avoids scrub forest; this may explain its absence in the
Balsas-Tepalcatepec Valley.

~Sonora michoacanensis michoacanensis~ (Duges)

_Contia michoacanensis_ Duges, _in_ Cope, Proc. Amer.
Philos. Soc., 22:178, 1885.--Michoacan. Type locality
restricted to Apatzingan, Michoacan, Mexico, by Smith and
Taylor (1950a:335).

_Sonora michoacanensis michoacanensis_, Stickel, Proc. Biol.
Soc. Washington, 56:116, October 19, 1943.

Apatzingan (3); Coalcoman (3); 12 km. S of Tzitzio.

These specimens, together with all known specimens from the Sierra del
Sur in Guerrero (KU 23790-1, MVZ 45123) and the upper Balsas Basin in
Puebla (UIMNH 41688), are referable to _S. m. michoacanensis_. The
dorsal pattern consists of a highly variable number of cross-bands of
red, white, and black. In the specimens from Michoacan there are as many
as 17 red cross-bands on the body. One specimen from Apatzingan (CNHM
37141) has just behind the head a white band, bordered on either side by
a narrow black band; posteriorly the body is uniform red. Two specimens
from Coalcoman (UMMZ 109905-6) have respectively 11 and 13 red
cross-bands and 20 and 17 white cross-bands, and the posterior part of
the body is devoid of red color. Other specimens from these localities
have red, black, and white cross-bands throughout the length of the
body.

_Sonora michoacanensis michoacanensis_ is distinguished from _S.
michoacanensis mutabilis_ by the presence of cross-bands on the tail in
the latter (Stickel, 1943:116). One specimen from Coalcoman (UMMZ
109904) has one narrow band on the tail; all others from Michoacan have
uniformly red tails.

Apparently _Sonora michoacanensis michoacanensis_ ranges in semi-arid
and arid habitats from the upper Balsas Basin in Puebla westward to the
lower slopes of the Sierra de Coalcoman, whereas _S. m. mutabilis_
lives in foothills of the Sierra Madre Occidental from southern Jalisco
to Nayarit. Zweifel (1959b:6) presented evidence to show that specimens
of _S. m. mutabilis_ supposedly from "Distrito Federal" probably bear
erroneous locality data.

~Tantilla bocourti~ (Guenther)

_Homalocranium bocourti_ Guenther, Biologia
Centrali-Americana, Reptilia, p. 149, 1895.--Guanajuato,
Guanajuato, Mexico.

_Tantilla bocourti_, Cope, Amer. Nat., 30:1021, December,
1896.

Carapan; Patzcuaro (2); between Zitacuaro and Rio Tuxpan
(11).

This smal