1951. _Pipistrellus hesperus potosinus_ Dalquest, Proc.
Biol. Soc. Washington, 64:105, August 24, type from Presa de
Guadalupe, San Luis Potosi.
_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.
=Eptesicus fuscus miradorensis= (H. Allen)