d, Copeia,
no. 1:112, March 17, 1961.

Apatzingan (31); Capirio (2); Charapendo; Cuatro Caminos
(22); El Sabino; Lombardia (9); Nueva Italia (8); Uruapan
(3).

The reasons for recognizing the population of _Thamnophis dorsalis_ in
the Tepalcatepec Valley as distinct from that on the surrounding
highlands are presented in the discussion of _Thamnophis dorsalis
cyclides_. In certain features of coloration and in the low numbers of
ventrals and caudals, _T. dorsalis postremus_ shows more resemblance to
_T. dorsalis sumichrasti_ than to _T. dorsalis cyclides_. According to
Milstead (1953:367), _T. dorsalis cyclides_ ranges southward from the
Rio Balsas in southwestern Mexico. If specimens could be obtained from
the upper Balsas Basin they might show that _T. dorsalis postremus_
inhabits that extensive basin.

In the Tepalcatepec Valley _T. dorsalis postremus_ is most frequently
found at night in the rainy season, at which time the snakes are
abundant near temporary pools where frogs are breeding. The absence of
specimens from the coastal lowlands of Guerrero, Michoacan, and Colima
indicate that, although the species inhabits the lowlands of the
Tepalcatepec Valley, its range does not include the coastal lowlands.

A female (UMMZ 119402 from Cuatro Caminos) having 139 ventrals and a
body length of 576 mm., on June 20, 1958, gave birth to 25 young, of
which 18 (9 males and 9 females) were preserved. In body length the
males varied from 132 to 141 (137.3) mm.; the females, 125 to 137
(133.1) mm. In tail length the males varied from 38 to 44 (42.4) mm.;
females, 35 to 42 (39.7) mm. The males have 138 to 147 (142.2) ventrals
and 70 to 75 (72.9) caudals; females have 131 to 140 (135.8) ventrals
and 63 to 71 (67.0) caudals.

~Thamnophis eques eques~ (Reuss)

_Coluber eques_ Reuss, Zool. Misc., p. 152, 1834.--Mexico.
Type locality restricted to Guadalajara, Jalisco, Mexico, by
Smith and Taylor (1950a:334).

_Thamnophis macrostemma macrostemma_, Smith and Taylor,
Bull. U. S. Natl. Mus., 187:163, October 5, 1945.

_Thamnophis subcarinata subcarinata_, Smith, Herpetologica,
5:63, May 31, 1949.

_Thamnophis eques eques_, Smith, Copeia, no. 2:139, June 8,
1951.

Jiquilpan; Lago de Cuitzeo; Lago de Patzcuaro (17);
Patzcuaro (5); Tangancicuaro; Tupataro (2); Undameo; Zacapu.

Although this snake has been collected in open pine-oak forest and in
oa