Quest 1948 Tadarida Mexicana 1 April 10 Punta San Felipe, 50 ft, Baja California Two caught by Dr. Benson that had flown into our skirting room separately at 10:30 and 11:00 P.M., while we were working on species. April 11 Several seen flying over beach at dusk. One shot by Murray. The Tadarida seem to fly singly and generally higher from the ground than the Pipistrellus hesperus, and are easily recognized as different from the Pipistrellus by their larger size and slower wing-beat. April 16 Cerro de Centinela 300 ft. 13 mi. WSW Mexicali, Baja California. One seen flying of over alluvial material of desert after sunrise by Dr. Benson. April 19 Cerro Pinto 30 ft. 20 mi. SSE Mexicali, Baja Calific. One female shot as it was flying at about 50 ft over open field, shot where field borders mesquite between 7:30 and 8:00 P.M. last night (# 78). April 30 Mission San Ignacio 500 ft Baja California. 46 caught, 19 & 27 F., in the old mission. The bats were found above the doorways in crevices formed by the wood moulding and in the attics of buildings adjoining the mission. The attics were inaccessible, but the bats were procured by poking through holes in the stone walls with consequent pouring out of the bats through the entrance to their roost. Hand nets were held over the holes.