The impression gained by examining many mixed colonies of _Antrozous_ and _Tadarida_ was that the former greatly outnumbered the latter. For example, a small colony of bats in an old barn near San Dimas Wash consisted of about thirty pallid bats and five freetails. Large numbers of wings of moths of the family _Sphingidae_, and legs and parts of the heads of Jerusalem crickets (_Stenopelmatus fuscus_) were beneath an _Antrozous_ night-roosting place in a barn near Upland. Pallid bats were collected in 1951, from April 16 to October 17 but probably were active in the area into November. Each of two pregnant females taken two miles northeast of San Dimas on April 20, 1951, carried two embryos 4 millimeters long. _Specimens examined._--Total, 6, distributed as follows: Los Angeles County: 2 mi. NE San Dimas, 1200 ft., 2 (1PC); Ontario, 1100 ft., 4 (3PC). Family MOLOSSIDAE =Tadarida mexicana= (Saussure) Mexican Free-tailed Bat This bat, regularly met with in the citrus belt at the coastal base of the range, occurred in small numbers with colonies of _Antrozous_, and was once found with a colony of _Eptesicus_ near Covina. None of the females taken in April 1951 was pregnant. _Specimens examined._--Los Angeles County: 2 mi. NE San Dimas, 1200 ft., 4. =Eumops perotis californicus= (Merriam) Mastiff Bat H. W. Grinnell (1918:373) mentioned individuals collected at Sierra Madre (at the coastal base of the San Gabriels west of the study area), and Sanborn (1932:351) reported specimens from Covina and Azusa. Probably this bat occurs locally all along the coastal base of the range. Family LEPORIDAE =Lepus californicus bennettii= Gray California Jack Rabbit This species was found in the coastal sage belt from Cajon Wash west to San Gabriel Canyon and was most plentiful in thin stands of sagebrush, and in and around citrus groves. Because of their preference for semi-open country, jack rabbits are absent from much of the coastal belt of sagebrush where the brush is fairly continuous, and they never were observed in the chaparral association. Coyotes catch many jack rabbits and regularly forage around the foothill borders of the citrus groves for cottontails and jack rabbits. A female examined on February 19, 1951, was pregnant, and one taken on March 15, 1951, carried three small embryos. _Specimens examined._--San Bernardino County: 2 mi. NW Upland, 1600 ft., 3 (PC). =Lepus californicus deserticola= Mearns California Jack Rabbit There was sign of jack rabbits along the desert slope of the San Gabriels up to about 6700 feet, one-half mile west of Big Pines. They were fairly common in the Joshua tree belt, occurred less commonly in the juniper belt, and were present locally in small numbers in the pinyon-juniper association.