The dense accumulations of mammalian remains encountered in the Pleistocene asphalt deposits of Rancho La Brea furnish mute evidence of the unusual conditions of miring and trapping that prevailed at this locality during the active periods of the tar pools. The abundance of skull and skeletal materials and the excellent state of preservation of the specimens suggest rather strongly that in the process of entombment the struggles of a mired form frequently hastened its total immersion and disappearance from the surface. <br /><br />Information derived from a study of the Rancho La Brea collection in the Los Angeles Museum clearly indicates that a rapid entombment of the mired hosts may not always have taken place. It seems safe to assume that in some instances the bodies of animals trapped in the tar were disturbed or dismembered and the skeletal elements scattered before actual deposition occurred. Moreover, it appears possible that osseous remains accumulated along or near the borders of the pools where the carcass of a mammal may have been subjected to the forces of the weather and to disturbance by other creatures before entering the asphalt record. An inference may be drawn therefore that members of the carnivore group were often attracted to the traps not only by the sense of sight but by the sense of smell as well, significant perhaps in accounting for the noticeable prevalence of such forms as the dire wolves (Alnocyon). <br /><br />It is intended in the present paper to direct attention to two types of evidence on which these assumptions are based.