12 



exclusion of typical leucopus, but associated with it in some 

 localities). 



Ic. Hesperomys (Vesperimus) leucopus eremicus (Bd.). 



Stn. Hexperomys eremicus^ Bd. M. N. A. 1857, 479. — Coues, Quad, of 

 Arizona, Am. Nat. i. 398. 



Hah. Yalleys of the Colorado and Gila Rivers. 

 Ohs. The soles in this variety, and in species No. 4, are quite 

 naked, but merely as an incident of their desert habitat. 



2. Hesperomys (Vesperimus) aureolus, (Aud. & Bach.) Wagn. 



Syn. Mm ( Galomi/.^) aureolus, Aud. & Bach., J. A. N. S. P. vi. 1842, 302 ; 



Q. N. A. ii. 1851, 303, pi. 95. 

 Hefiperomys mireolus, Wagn., Wieg. Arch. ii. 1843, 51. 

 ? Arvicola nuttaUi, Harlan, Am. Month. Journ. 1832, 446; Med. and 



Phys. Res. 1835, 55, pi. 00. 

 Hesperomys nuttaUi, Baird, M. N. A. 1857, 467. 



Hab. Central and Southern States. 



3. Hesperomys (Vesperimus) miohiganeiisis, (Aud. & Bach.) Wagn. 



Syn. 3Ius micJitganensis, Aud. & Bach. J. A. N. S. Phila. viii. 1842, 304 ; 

 Quad. N. A. iii. 1854, 326. 

 Hesperomys micMganensis, "Wagn., Wieg. Arch. ii. 1843, 51. 

 Ifus bairdii, Hoy & Kenn., U. S. Patent Office Rep. Agric. for 1856, 

 (1857) 92, pi. xi. 



Hab. Upper Mississippi Yalley, especially Illinois, Michigan, 

 and Wisconsin. 



4. Hesperomys (Vesperimus) californicus, (Gambel) Baird. 



Syn. 3fus californicus, Gamb., P. A. N. S. P. iv. 1848, 78 (Monterey). 

 Hesperomys californicus, Baird, M. N. A. 1857, 478. 

 Hesperomys parasiticus, Cooper's MSS., Bd., op. cit. 479 (in text). 



Hab. Southern and Lower California. 



5. Hesperomys (Vesperimus') aztecus, De Sauss. 



Syn. Hesperomys aztecus, De Sauss., R. M. Z. 1860, p. 00 (p. 22 of the re- 

 print) . 



Hab. "Mexico." Cape St. Lucas. 



Obs. This species appears to belong strictly to the Vesjyerimus 

 group. It is about the size and form of V. leucopus, but the tail is 

 nearly naked and scarcely bicolor, while the colors are notably 

 different; they differ just as those of Ncotoma ferruginea do from 



' I liave not determined the presence of cheek pouches in this or tlie suc- 

 ceeding species ; in all other respects they are truly Vesperimus, and they 

 doubtless possess them. 



