Quast 1948 Pipistrellus hesperus 6 June 23 Mulege, 250 ft Baja California Several hundred seen this evening just after sunset. They were flying at a very high altitude from the mountains south of us towards the palms in the valley floor. For a while a large "cloud" of bats and Nighthawks circled far above our heads to dissolve completely in the next fifteen minutes. The large number of Pipistrellus disappeared from the sky to feed among the palms and brush of the canyon floor, their being seen feeding low thereafter. Other species of small bats may have been present but only this species was shot. In the later periods they fed about the same habitat as the Eptesicus fuscus being seen more frequently over the open field with low brush however. June 29 Santa Rosalia, 100 ft Baja California One shot by Dr. Benson and one netted by myself as they flew over low brush on flat in back of beach about ½ mile north of this town. Feeding in same habitat as a larger bat - probably Eptesicus fuscus. Time of obtaining the specimens was at dark (about 8:30 PM). June 30 San Lucero, 100 ft, 5 mi S. Santa Rosalia, Baja California This species appeared at this place (see Journal pg. 148) ten minutes after the first Nighthawk was seen (sunset). They were feeding over the brush by the pond and over a nearby cornfield. Eptesicus fuscus appeared ten minutes later than the Pipistrellus. It was noticed