136 
1855. Neotoma ‘nucropus, Baird, Proc. Acad. Nat. Sci., Phila., vii, 1855, 
833; M. N. A., 1857, 492; U. 8. and Mex. Bound. Surv., ii, pt. 
11, 1859; Mamm., p. 44. 
Specific Characters.—Length about 6 inches ; tail about 6; hind foot 1.50; 
skull averaging 2 inches. Tail scant-hairy, bicolor, grayish and whitish. 
Adults with general body colors of Norway Rais, but more fulvous on 
the sides; white below; young gray or slate color. Tubercles blackish ; 
toes and palms flesh-colored; tips white; back of hands and the feet 
snowy white. 
Distribution.—Found in southern United States and northern Mexico; 
north to Maryland (Audubon), New York (Bell), Massachusetts (Gibbs), 
Dakota, Illinois, Kansas, and Arkansas (Coues); identified in Ohio by 
Dr. Byrnes, who, as I am informed by Mr. Langdon, “captured a speci- 
men that was abandoned near New Philadelphia, Ohio.” 
Professor M. V. B. Knox, of Baker University, Kansas, states that the 
species is common along streams in middle and western Kansas, where 
they build nests by piling up sticks and pieces of bark to the height of 
two or three feet, often about the base of a tree orstump. In these piles 
they construct a nest of dried leaves and grass. 
GENUS HerspERoMys Waterhouse. 
Hesperomys is a tribal rather than a generic name, including, according 
to Dr. Coues, in North America, Vesperimus, Onychomys, Oryzomys, Ocheto- 
don, Sigmedon, and Neotoma, with as many South American genera or 
sub-genera besides. The same author says: “In our comparative ig- 
norance of South American forms, we shall not venture upon any diag- 
nosis or description of the full genus Hesperomys.” 
SUB-GENUS VESPERIMUS Coues. 
-—- Musculus, Raf., Am. Month. Mag.. 111, 1818, 446. 
= Hesperomys, Baird, Mam. N. A., 1857, 458. 
— Vesperimus, Coues, Proc. Acad. Nat. Sci.. Phila., 1874, 178 (type Mus 
leucopus). 
< Hesperomys, of North American writers. 
> Calomys, Aud. & Bach., Quad. N. A., 11, 1851, 308. 
Sub-generic Characters.—Of medium and small size, lithe form, and 
quick movement; eyes large and prominent; ears rounded, large, thin, 
gcant-pilous, antitragus evident but not valvular; claws weak ; hind legs 
and feet long, the latter with six large conical tubercles; hind feet naked 
or scant-furred on posterior third; tail terete, slender, closely hairy, 
