ne blocks, and each burrow where I caught a mouse has a pile of excavated earth, like a tiny gopher mound." The trapping area was at an elevation of approximately 2800 feet on the steep sides of a small hill on top of which the field camp was situated. Schaldach indicated that this locality was transitional between arid tropical and humid tropical conditions. On January 13, 1950, a female taken was lactating and had five recent placental scars; another taken the same day also had five placental scars.
Measurements.--Average and extreme measurements of seven adult males and six adult females of P. ochraventer from the type locality are, respectively, as follows: Total length, 238.0 (227-249), 236.5 (226-248); length of tail, 124.4 (117-127), 122.2 (116-128); length of hind foot, 25.6 (24-26), 25.5 (25-26); length of ear from notch, 20.9 (20-21), 20.7 (20-21); greatest length of skull, 31.0 (30.6-31.9), 30.8 (30.5-31.0); basilar length, 23.3 (22.7-23.8), 23.4 (23.0-23.9); zygomatic brea