Quart 1948 Journal 126 June 19 San Jorge, 50 ft, 25°44'N, 112°07'W, Baja California. The only places visible from camp where mangroves are not growing is this place and the southern outlet of the estero. South of camp about 75 yards a large patch of Mangroves occurs that is circular in outline and of approximately 50 yards in diameter. Despite the fact that the area is flooded at high tide, Museum special traps set in the area last night by Dr. Benson & Murray caught some Peromyscus maniculatus. The hills on the east side of the estero are mainly of yellowish sand and shell and grown with clumps of Ocotillo, Pitaya aquia, Cholla and Limboi. By far the greatest number of plants is the Ocotillo which is covered with the moss-like Orchillo parasite. Clear sand that is quite firmly packed occurs between these bushes and at this time is heavily covered with the tracks and burrows of pocket mice. The north end of the estero ends in mangroves beyond which is a sandy flat continuous with the sand dunes on the west side. To the south and at the estero outlet small sand cliffs are visible apparently where the tidal waters are undercutting the sand dunes. This estero is supposed to be the