Quest 1948 Macroscus californicus June 14 Mina Palmer del Medio, 400 ft, 4 mi ESE Pescadero Baja California To be standing outside of the mine when one group of about 20 of this species was called out by someone within. I was surprised to see them all group together in a flock and fly over the hill as a unit rather than each in- dividual picking his own way. This grouping tendency was noticed again when Dr Benson released 7 males and 2 females from those he had caught in the mine; when released one by one, the first bat would circle as if lacking confidence until joined by one or two others, and then, as a group, fly to other sections. These bats fly slowly and quietly and seem to use their eyes and ears a great deal while flying. June 22 8.3 mi by road N Campoli; 26°32'N, 111°35'W, Baja California Six taken from a small cave in a lava con- glomerate cliff 50 yds N of the road here. The cave was about 10 feet deep and ended in a large crevice in which the bats were found hanging. About 50 individuals in the colony - no other kind were present. The ? I put up had one embryo of 26 mm. When the bats were taken out of the sacks in which they had been kept one was found to have its tail, uropatagium, and one leg entirely eaten off. A Wood Rat had also occupied the small cave, scattering Cholla thistles about it.