Quast 1948 Journal 148 June 30 Las Lucias, 100 ft 3 mi S. Santa Rosalia, Baja California. A possible additional cause of the sparse vegetation is the chemical smoke of a copper reduction plant that is in continuous operation at Santa Rosalia. The arroyo that runs east from this place (leading) is of slight gradient and changes from a broad boulder-strown streambed here to sand at its mouth, about two miles east of here, at which a small inlet is to be found. We stopped by the road south of town, between it and a small ranch called Las Cuevitas. On the rise exists a small dam for irrigation pur- purposes that is filled at night but contains water in a very shallow pond all day. The dimensions of the shallow pond was about 20 by 8 feet, & that of its limits when filled about 40 x 15 feet. Next to the pond towards town a cornfield exists in which patches of alfalfa are also grown. Before sunset a few Violet-green Swallows were seen flying about the pond and the scanty Copal & Palo Verde trees at that place. Just after sunset many Nighthawks appeared, some flying a few feet above the ground, some diving and skimming the pond surface to drink, and others circling the cornfield or flying high in the air. Ten minute after the first Nighthawk was seen the first Pipistrellus lasperna was seen, to be followed in ten minutes by