Measurements.—External measurements of two males (58849, 58848) from 8 km. west and 10 km. north of El Encino and a male (60296) from Rancho Pano Ayuctle are, respectively, as follows: 78, 81, 83; 36, 38, 36; 10, 10, 9; 11, 11, 11; length of forearm, 33.1, 32.0, —; length of tibia, 14.6, 13.4, 13.0. Some cranial measurements of the two specimens from northwest of El Encino are: greatest length of skull, 12.8, 12.9; breadth of braincase, 6.5, 6.5; length of maxillary tooth-row, 4.0, 4.1.
Records of occurrence.—Specimens examined, 3: 8 km. W, 10 km. N El Encino, 400 ft., 2; Rancho Pano Ayuctle, 6 mi. N Gómez Farías, 300 ft., 1.
Additional record: Matamoros (H. Allen, 1894:128).
Pipistrellus hesperus potosinus Dalquest
Western Pipistrelle
1951. Pipistrellus hesperus potosinus Dalquest, Proc. Biol. Soc. Washington, 64:105, August 24, type from Presa de Guadalupe, San Luis Potosí.
Distribution in Tamaulipas.—Probably occurs throughout southwest part, but presently known only from Joya Verde.
The specimens reported herein were shot in July in a canyon that contained some standing water. According to the field notes of the collector (Schaldach), individuals of this bat in Tamaulipas flew later, in his experience, than bats of the same species in Sonora, Arizona and Coahuila, not emerging until it was almost fully dark.
Pipistrellus hesperus from Tamaulipas is identified as P. h. potosinus owing to the dark color, but the averages of some measurements differ slightly from those given by Dalquest (1951:106) for potosinus as follows: tail and ear shorter; foot larger; condylobasal length and cranial breadth less.
Measurements.—Average and extreme external and cranial measurements of five males from Joya Verde are: 73.2 (70-75); 27 (26-28); 7 (7); 12.4 (12-13); length of forearm, 31.0 (29.5-31.5); greatest length of skull, 12.4 (12.2-12.8); condylobasal length, 11.8 (11.4-12.3); breadth of braincase, 6.3 (6.0-6.5). Corresponding measurements of three females (60204, 60209, 60210) from the same locality are: 72, 78, 76; 27, 33, 35; 7, 7, 7; 12, 12, 12; 31, 31, 32; 12.3, 12.9, 13.5; 11.7, 12.2, —; 6.0, 6.6, 6.1.
Records of occurrence.—Specimens examined, 8, from Joya Verde, 35 km. SW Cd. Victoria, 3800 ft.