Quast 1948 Pipistrellus hesperna 2 April 17 Cerro Prieto 30 ft 20 mi SSE Mexicali Baja Calif. Dr. Benson also shot me at the same time 100 yds. distant. The Pipistrelles were not noted until it was quite dark and were feeding when seen. My specimen was not put up because of drying out overnight and blasted condition. April 19 One shot at dusk (7:45 P.M.) yesterday as it was flying over open field. (♀ #28) May 3 Mulege 25± ft Baja California 3 ♂ + 2 ♀ shot at dusk by Murray, Tevis, and Dr Benson in a small rocky canyon above the creek. Dr. Benson said that they were then in very large numbers. Specimens were put up by Dr. Benson under this date. May 8 Rancho Cadejo S.W. end Baha Concepcion Baja California One male shot last evening at dusk by Murray. About five others seen, feeding singly. May 10 San Jose de Comondú 700 ft Baja California Two shot by myself last evening between 7:15 and 7:45 P.M. They were feeding among the palm trees of the arroyo floor accompanied by Eptesicus fuscus which started flying about 7:30 P.M. So far I have noticed that the Pipistrellus hesperna is the first bat to be seen flying in the afternoon, appearing here at sunset. They appear to be very common here. Minimum temp. last night was 56° F. Only one specimen saved (#163).