Quest 1948 Eptesicus fuscus 5 June 12 Pozo Grande, 25°46'N, 112°02'W, Baja California widely apart, lead turned back with jaws opened widely and a furious chattering accompanying them. If two of this species that are wounded and excited are brought close together, the result is usually a furious grappling and biting with loud chattering, the two bats having to be pulled apart. Some are so furious when hit that they will attempt to stand up to bite the approaching hand. This could not be called bluffing but sheer aggression. June 22 Santa Rosalillo, 25°-ft S.E. end Bahia de Concepcion, Baja Calif. Five or six of this species appeared over the reef after 7:40 P.M. When first seen two of them were flying toward us and then veered to our right to feed among the tall Cardones and over the coral and leeward side of a Palo San Juan and a Mesquite that are assoc- iated with the coral. The one Eptesicus I shot kept feeding over the coral and its route extended slightly past the two before mentioned trees set on opposite sides of the coral. A small bat had also taken up the same route of feeding and kept flying back and forth in its area. This species, Eptesicus fuscus, quite obviously has the tendency to establish favorite feeding areas and begins working them before dark. The specimen ob- tained #433 was a female with no embryo.