ILLUSTRATIONS IN THE TEXT. 



Page. 



Didelphys virginiana 2 



Balaena glacialis 7 



Halaenopti-ra acutorostrata 12 



Physetir inacmcephalus 15 



Mesoplodon densirostris 17 



Monodon moiioceras 19 



Phocaena dalli 21 



Lagenorhynchus albirostris 26 



Prodelphiniis plagiodon 31 



Sciurus (Parasciurus) niger 51 



Sciurus (Neosciurus) carolinensis 54 



Sciurus (Hesperosciurus) griseus 56 



Sciurus (Otosciurus) aberti ■. . 58 



Sciurus (Araeosciurusi arizonensis 59 



Sciurus (Taniiasciurusi hudsonius 61 



Tamias (Eutatuiasl dorsalis 68 



S[)ermopliilus (Callospermophilus) lateralis 82 



Sptrninphilus (Ammospermophiius) leucurus 85 



Spermophilus (Otospermophilus) gramniurus 87 



Spef mophilus (Colobotis) kadiacensis 90 



Speniiopliilu!; (Xcrospermophilus) microspilotus 95 



Spermophilus ( Ictidomysi i3-lineatus 99 



Cynomys ludovicianus 103 



Arclf>niys nionax 105 



Sciuropterus volans 108 



Haplodontia californica 113 



Castor canadensis 115 



Mus rattus 118 



Onychoniys leucogaster 119 



Peromyscus aniericanus 124 



Sigmodon hispidus 143 



Oryzomys aquaticus 146 



Reithrodontoniys k-cnntii 149 



Neotonia tloridana 155 



Nentoma (Teononia) cinerea 163 



Phonaconiys nrnphilus 167 



Evotomys gappcri 170 



Microtus pennsylvanicus 179 



Microtus ( Lagurus] curlatus 194 



Microlus ( Pedoniys) austerus 196 



Microtus ( Fitymys) pinetoruni 198 



Microtus (Chiloius) oregoni 199 



Microtus (Arvicola) macropus 201 



Microtus (Neoliber) alleni 202 



