MERRIAMI GROUP MERRIAMI GROUP _Dipodomys merriami_ _Dipodomys merriami_ _Dipodomys nitratoides_ _Dipodomys nitratoides_ _Dipodomys platycephalus_ _Dipodomys platycephalus_ _Dipodomys margaritae_ _Dipodomys margaritae_ _Dipodomys insularis_ _Dipodomys insularis_ _Dipodomys mitchelli_ _Dipodomys mitchelli_ _Dipodomys phillipsii_ _Dipodomys ornatus_ _Dipodomys elator_ ORDII GROUP ORDII GROUP _Dipodomys ordii_ _Dipodomys ordii_ _Dipodomys microps_ COMPACTUS GROUP NOW IN ORDII GROUP ABOVE _Dipodomys compactus_ _Dipodomys sennetti_ AGILIS GROUP NOW IN HEERMANNI GROUP ABOVE _Dipodomys agilis_ _Dipodomys venustus_ _Dipodomys elephantinus_ MICROPS GROUP NOW IN ORDII GROUP ABOVE _Dipodomys microps_ _Dipodomys levipes_ DESERTI GROUP DESERTI GROUP _Dipodomys deserti_ _Dipodomys deserti_ WERE IN HEERMANI GROUP ABOVE PANAMINTINUS GROUP _Dipodomys panamintinus_ _Dipodomys stephensi_ Names of the subspecies are omitted from the groups named above and only the names of full species, as understood by Grinnell and as understood now, have been used. It will be noted that the phylogenetic order follows that of Grinnell rather than the one proposed herein. The fossil record of the kangaroo rats is so scanty that one can but speculate on the evolutionary sequence. Wood (1935) presented a diagnosis of the early phyletic history up to and through _Cupidinimus_; this is probably as correct as can be made. I cannot, however, share his view that the recent species of _Dipodomys_ have originated from a descendant of _Cupidinimus nebraskensis_; instead, I think that the Recent species originated from some unknown ancestor in the southwest. [Illustration: FIG. 21. Diagrammatic representation of the relationships and history of the Recent species _Dipodomys_.]