Cushing's (1945:182-185) report on his study of the rodents and lagomorphs includes a description of an extinct pygmy species of rabbit, _Sylvilagus leonensis_. He records three kinds of pocket gophers from San Josecito; Cushing was able to separate the genus Thomomys from two unidentified geomyids (_loc. cit._:185). These prove to belong to the genera _Cratogeomys_ and _Heterogeomys_; the materials are described below. Cushing records also larger mammals, including the antilocaprid (_Stockoceros conklingi_), saber-toothed cat (_Smilodon_), dire wolf (_Aenocyon_), a large oviboid (_Preptoceras_), and deer (_loc. cit._:182). More recently Findley (1953:633-639) has written on the remains of the family Soricidae taken from the cave, and Hooper (1952:59) has studied the bones of the genus _Reithrodontomys_ and found them not different from those of _R. megalotis_ that inhabits the region of the cave today. Handley (1955:48) has described a new species of plecotine bat, _Corynorhinus tetralophodon_, from the collection. Jones (1958:389-396) published an account of the bats of San Josecito, and described a new vampire bat, _Desmodus stocki_, from the cave. Jakway (1958:313-327) has reported on the lagomorphs and rodents in detail, and compared this part of the cave fauna with that of Rancho La Brea and Papago Spring Cave, Arizona. Jakway (_lit. cit._:323-324) suggests that the fauna from San Josecito is late Pleistocene, probably contemporaneous with the remains from Papago Spring Cave and pre-Rancholabrean. I thank Professor E. Raymond Hall and Dr. Robert W. Wilson for their permission to examine this material and for critical comments and advice on the manuscript. The drawings were made by Miss Lucy Remple. The specimens are a part of the collection of fossil vertebrates formerly belonging to the California Institute of Technology, but now the property of the Los Angeles County Museum. The specimens had been lent by the late Professor Chester Stock to Professor Hall and Dr. Wilson for study and report. All measurements herein are in millimeters. #Thomomys umbrinus# (Richardson)