Quest 1948 Journal 139 June 26 Arroyo San Luis, 800+ ft., 7 mi W. Calmell, Baja Calif. the horizontal tunnels at least 40 feet above that of the wash and arroyo it faces. We entered the mine about an hour before sunset and noticed bats flying when we had traversed 1/3 its length and had entered complete darkness. Upon pursuing the bats down the tunnel we finally reached the end and a side passageway near the end which when blocked off yielded several Choeronycteris mexicana. Both lactating females and young bats, 3/4 grown, of this species were obtained. Also obtained this afternoon were three Corynorhinus, two of which were picked off the rough 5 1/2 foot tunnel ceiling about half the distance from the entrance. Both were in a torpid state, their long ears tightly rolled at the sides of their heads. The two were not close together but separated by at least 15 feet and were not disturbed by our passing underneath them with flash- lights - our not noticing them until we had passed one, the other being collected on the way out. One was obtained by Murray with his hand net. One Myotis californicus was seen but flew past us out of the tunnel entrance into the daylight. The four of us then climbed the hill to