104 ZOOLOGY. 



Far. EEEMICUS. 



Hcspcromys crcmicm, BAIRD, Mamm. N. A., 1857, 479. COUES, Am. Nat., i, 1807, 398. 

 Hesperomys (Vesperimus) leucopus cremicus, COUES, Proc. Acad. Nat. Sci. Philn., 1874, 



180, (valley of the Gila aud Colorado). 

 The following species of this same section Avill probably be found in 



Arizona : 



HESPEEOMYS (VESPERIMUS) CAL1FOENICUS, (Gauib.) Bd. 



Cnliforniaii illouse. 



Mm caUfornicus, GAME., P. A. N. S. P., iv, 1848, 78 (Monterey). 

 Ilcsperomys caUfornicus, BAJRD, M. N. A., 1857, 478. 

 Hcupcromys parasiticws, COOPER'S MSS. BD., op. cit., 479 (in text). 

 Hcsi>eromys ( Vcspcrimus) californicus, COUES, Proc. Acad. Nat. Sci. Phila, 1874, 180. 

 UAB. Southern and Lower California. 



Subgenus ONYCHOMYS, Baird. 



lli/pudccus (sp.), MAXIM., Eeise, ii, 1841, 99, nee auct. 

 Man (sp.), AUD. & BACH., Q. N. A., ii, 1851, 327 (missouriensis). 



Hcspcromys subg. Onychomys, BAIRD, M. N. A., 1857. 458 (type Hypudwitti leucogaster, 

 Maxim.). COUES, Proc. Acad. Nat. Sci. Phila., 1874, 182. 



To the single known species of this genus, Dr. Coues lately added a 

 second, discovered in Arizona. The two may be thus distinguished : 

 .. Tail much less than half the head aud body, scarcely twice the 

 hind foot. Fore foot more than half the hind foot. Ear about 

 0.50 high. Beneath snow-white; above mouse-brown with darker 



dorsal area LEUCOGASTER. 



b. Tail nearly half the head and body, about 2| times the hind foot. 

 Fore foot only half the hind foot. Ear about 0.75 high ; beneath 

 tawny white; above brownish-fulvous, without darker dorsal 

 area (var.?) TORRIDUS. 



HESPEROMYS (ONYCHOMYS) TOEEIDUS, Coues. 



llespcromys (Onychomys) torridus, COUES, Proc. Acad. Nat. Sci. Phila., 1874, 183. 



DIAG. Eesembling 0. leucogaster ; tail longer, ears larger, soles less hairy, fore 

 claws weaker. Coloration much more yellowish ; no darker dorsal area ; snout, feet, 

 aud all under parts tawny-white; dusky stripe on top of tail very narrow, not reaching 

 the tip. Length of head aud body, 3.75 ; of tail, 2.00 ; of fore foot, 0.40 ; hind foot, 0.80 ; 

 ear about 0.75 above notch. Only two pair (inguinal) of teats discovered. (Type No. 

 9886, Mus. S. I.) 



llAB. Arizona. 



Genus OCHETODON, Coues. 



Mus (sp.), AUD. & BACII. 



Hesperomys (sp.), WAGNER. 



L'i'ithrodon, LECONTE, P. A. N. S. P., 1853, 413. BAIRD, M. N. A., 1857, 447; but 



not of \\'(iti'i-/:/ii/x, . 

 Ochclodon, COUES, Proc. Acad. Nat. Sci. Phila., 1874, 184 (type O. humiliis). 



