R.K. Selander, 1952 July 25 Rio Metztitlan, Hidalgo, Mexico without fording the river. We were reluctant to attempt a crossing, so we made camp near the ford -- Rio Metztitlan, 4000 ft., 20 miles N Atotonilcos, Hidalgo, Mexico. Set up our tents about 100 feet from the river, beneath a canopy of black walnut trees. We are camped in a rather narrow arroyo. There is a small store and a number of homes near our camp. Along the river on both sides there are small Mexican houses and corn-fields. The river is extremely muddy; about 30 yards wide. Extending on either side of the river for a quarter of a mile or so (often less) is a narrow flood plain and, then, the corn fields. Willow bushes and trees) are thick along the river, forming a well- developed riparian habitat. A large grove, having the appearance of bamboo, occurs in stands along the river. A number of irrigation ditches have been made by the Mexicans & there are usually lined with willows. Giant black walnut trees line both sides of the river. Mosquitoes occur in the drier spots, often quite near the river, but especially on the slopes well away from the river. On the rather steep slope of the arroyo there is a thick forest of cardon cactus. Tuna cactus is rather uncommon. Mosquito common among the cardon cactus. This forest is rather extensively distributed