180 PROCEEDINGS OF THE ACADEMY OP 



exclusion of typical leucopus, but associated with it iu some 

 localities), 



1c. Hesperomys (Vesperimus) leucopus eremicus (Bd.). 



Syn. Iletperoinys ereiiiicus, Bd. M. N. A. 1857, 479. Coues, Quad, of 

 Arizona, Am. Nat. i. 398. 



Hab. Yalleys of the Colorado and Gila Rivers. 

 Obs. The soles in this variety, and in species Xo. 4, are quite 

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



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



Syn. 3fus [Calomys) aureolus, And. & Bach., J. A. N. S. P. vi. 1842, 303 ; 



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

 Hesperomys aureolus, Wagn., Wieg. Arch. ii. 1843, 51. 

 ? Arvicola nuttalli, Harlan, Am. Mouth. Journ. 1833, 446 ; Med. and 



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

 Hesperomys mittalh', Baird, M. N. A. 1857, 467. , 



Hab. Central and Southern States. 



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



Syn. Mus michiganouis, Aud. & Bach. J. A. N. S. Phila. viii. 1843, 304; 

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

 Hesperom,ys micMganensis, Wagn., Wieg. Arch. ii. 1843, 51. 

 Mm bairdii, Hoy & Keun., U. S. Patent Office Rep. Agric. for 1856, 

 (1857) 93, pi. xi. 



Hab. Upper Mississippi Yalley, especially Illinois, Michigan, 

 and Wisconsin. 



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



Syn, Mus 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 Vesjjerimus 

 group. It is about tlie 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 Neotoma ferruginea do from 



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

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

 doubtless possess them. 



