R.K. Selander, 1952 July 22 35 mi. S EL Entranque, 5000 ft., Durango, Mexico. Swallow flying over river bed. left camp at 10:30, will continue along highway to Durango. 14 mi. N Rincon de Romos, 6200 ft., Aguascalientes Mexico. Camp'd in stand of mesquite trees and cactus just off the highway at 9:00. Ate and went to bed; very tired. No melvols came to light. Slight rain drizzle during the night; rather cold. July 23 Up at 6:30; cloudy, overcast, rather cold. Noted a strike near camp. Birds uncommon. Broke camp at 8:30, continuing southward. Will stop at Chester Lamb's in Guanajuato to pick up collecting equipment left by Dr. Miller and to get information on whereabouts of good "wren-country". The country throughout much of Durango, Zacatecas and Aguascalientes is good farm land, although undeveloped. Very few places visible from the highway where C. duranicapillus could be expected to occur. This species apparently does not occur in the type of cactus having ovate branches [picture] (=tuna) (cactus) and which is so common in Durango and Zacatecas. Perhaps they require a more finely branching cactus so that the nest can be constructed in such a position as to have the entrance hole protected by spiny branches, [No. See beyond]