The two subspecies of the Violet-green Swallow, thalassina and lepida, intergrade in Coahuila. Specimens from different localities in the State represent various stages of intergradation between the two subspecies; generally those from northern Coahuila seem to be closer to T. t. lepida, and those from southern Coahuila are closer to T. t. thalassina. Nos. 31471-31473 are intergrades between T. t. thalassina and T. t. lepida; in size the three resemble T. t. thalassina, but in green, rather than purple, backs and scapulars resemble T. t. lepida. The rumps of Nos. 31471-31473 show some purple with the green, but are nearer thalassina in this character.
Gonadal sizes (testes 10×7, 10×8 mm., one ovum 6 mm.) indicate that the Violet-green Swallow breeds in the Sierra del Pino.
*Tachycineta thalassina lepida Mearns.—Miller (1955a:167) reported that Violet-green Swallows taken in Boquillas Canyon of the Sierra del Carmen are intermediate between T. t. lepida and thalassina; however, he referred his sample to lepida on the basis of short wing.
Iridoprocne bicolor (Vieillot).—Miller, Friedmann, Griscom, and Moore (1957:114) reported the Tree Swallow from Hipólito on February 22.
Stelgidopteryx ruficollis psammochrous Griscom.—Miller, Friedmann, Griscom, and Moore (1957:111) reported this subspecies of the Rough-winged Swallow from Saltillo.
*Hirundo rustica erythrogaster Boddaert.—Burleigh and Lowery (1942:195) stated that the Barn Swallow was the most abundant swallow "about Saltillo." Because these swallows occupied houses about Saltillo and neighboring villages, Burleigh and Lowery (loc. cit.) concluded that the species nests commonly in the Saltillo area. Findley saw Barn Swallows 2 mi. S and 11 mi. E Nava, 810 feet, on June 15, 1952. Dickerman observed them at San Marcos (=20 mi. S Cuatro Ciénegas) on May 4, 1954.
*Petrochelidon pyrrhonota minima van Rossem and Hachisuka.—Specimens examined: total 2: ♂ ♂ 31585-31586 from 14 mi. W San Antonio de las Alazanas, April 9, 1954.
Burleigh and Lowery (1942:196) noted the Cliff Swallow "in small numbers about Saltillo and the nearby villages" where the species "showed evidence of beginning to nest in many of the houses...." They (loc. cit.) found Cliff Swallows also at the Chorro del Agua and Diamante Valley. According to Dickerman, Nos. 31585-31586 were from a colony, members of which were collecting mud at a stock tank.
*Petrochelidon fulva pallida Nelson.—The Cave Swallow seems to be uncommon in eastern Coahuila. Selander and Baker (1957:345) list Saltillo, Sabinas, and Monclova as the three known localities for this swallow in the State.
*Progne subis subis (Linnaeus).—Miller, Friedmann, Griscom, and Moore (1957:107) reported, presumably on the basis of a published record not found by me, that the Purple Martin breeds in Coahuila.