_Thamnophis vicinus_ Smith, Zoologica, 27:104, October 23, 1942.--Temazcal, Michoacán, México. _Thamnophis dorsalis cyclides_, Fitch and Milstead, Copeia, no. 1:112, March 17, 1961. Barolosa; Coalcomán; Dos Aguas (3); Los Reyes; Morelia (16); Opopeo; Pino Gordo; Tacícuaro (16); Tancítaro (14); Tangamandapio (2); Temazcal (2); Tzintzuntzan; Uruapan. The snakes comprising the former _Thamnophis eques_-group have undergone extensive taxonomic and nomenclatural shuffling by Smith (1942 and 1951), Bogert and Oliver (1945), Milstead (1953), and Fitch and Milstead (1961). Smith recognized in Michoacán three members of the _T. eques_ (= _dorsalis_) complex: _eques eques_, _eques postremus_, and _vicinus_. Later, Smith (1951) showed that the specific name _eques_ had been misapplied, so that _T. eques eques_ became _T. cyrtopsis cyclides_, and _T. eques postremus_ became _T. cyrtopsis postremus_; under this arrangement _T. vicinus_ stood unchanged. In the meantime, Bogert and Oliver (1945:359) presented a reinterpretation of Smith's data and suggested that _T. vicinus_, which differs from _T. dorsalis cyclides_ only in lacking a middorsal stripe, "... is not a species, but only a pattern phase, possibly a simple mutant of _T. e. eques_" (= _T. dorsalis cyclides_, by present arrangement). Milstead (1953) agreed with Bogert and Oliver on the status of _T. vicinus_; furthermore, on the basis of only a few specimens, Milstead concluded that _T. cyrtopsis postremus_ was not subspecifically distinct from _T. cyrtopsis cyclides_. Recently, Fitch and Milstead (1961) showed that _Thamnophis dorsalis_ Baird and Girard (1853) was the correct name for the snakes that had been recognized as _Thamnophis cyrtopsis_ Kennicott (1860). Consequently, the snakes referred to _T. eques eques_ by Smith (1942) and to _T. cyrtopsis cyclides_ by Smith (1951) and Milstead (1953) are now _T. dorsalis cyclides_. Aside from one specimen from Temazcal and nine from Morelia (paratypes of _T. vicinus_), only two other specimens completely lacking the middorsal stripe have been seen; one is a male (UMMZ 102510) having 161 ventrals and an incomplete tail from Pino Gordo, and the other is a male (CNHM 39060) from Tancítaro having 158 ventrals and an incomplete tail. A female from Tancítaro (CNHM 39061) having 153 ventrals and 77 caudals has no lateral stripes and only a narrow middorsal stripe on the anterior part of the body. Throughout the region where _T. vicinus_-like snakes have been found, typical _T. dorsalis cyclides_ occurs in much greater numbers. I concur with Bogert and Oliver in placing _T. vicinus_ as a synonym of _T. dorsalis cyclides_. [Illustration: FIG. 10. Dorsal color pattern of _Thamnophis dorsalis cyclides_ (A) and _Thamnophis dorsalis postremus_ (B).]