Munzay 1948 Journal May 7 Bahia Concepcion, 13 mi SE Mulege', Baja California probably many years accumulation of quano with dirt blown in. At the rear was a very small hole through which Dr. Benson entered and found another broad chamber about 3 feet high becoming shallower at the sides. This in turn led to another, much branched compartment. All apparently is a natural formation. In the inner part he found a great number of bats, of which he netted many, and the rest of [illegible] got more as they flew into the outer chamber. They were mostly Macrotus californicus, some Mormoops megalophylla, and a few of what are probably Septomylotis. After taking a necessary bath in the stream we took off, driving over rocky terrain and following fairly close to the bay. Made camp under a cave-like overhanging rock of volcanic conglomerate, beside the road. It is only a few feet from the shore of a circular inlet like a small bay. This is sheltered by steep rocky hills all the way around. On the northwest a narrow channel leads into a small estero very thickly grown with mangroves. The shore around us is clean shell fragment sand with some salicornia.