RODENTIA-MURINAE-NEOTOMA FLORIDANA. 
487 
elongated; the orbits much indented, the frontal space between them very narrow, especially 
behind. In both, the malar bone is very short, the posterior margin of the palate, between the 
last molars. In both, the nasal branch of the upper maxillary passes back of the end of the 
nasal, as in Sigmodon, instead of terminating in the same line, as in Mus decumanus. The 
upper incisors in both sections are almost as wide as deep, and have the anterior surfaces plane, 
bevelled off a little at the corners, instead of rounded completely, as in Sigmodon. The shape of 
the lower jaw is much like that of Sigmodon. 
Species of this genus are found throughout most of North America. One inhabits the south 
Atlantic and Gulf States, sending stragglers further north ; one belongs to eastern Texas and 
Mexico, and the others belong to the more western regions. As already remarked, a fossil 
species occurs in Pennsylvania. 
The following synopsis may serve to facilitate the determination of the species of Neotoma: 
A.— Tail scant haired, (as in the rats.) 
a. Feet entirely white ; tail not longer than the body alone ; lighter beneath. 
1. Size of the black rat. Tail about as long as the body alone. Color of the 
Norway or brown rat. Hind feet, 1.40 to 1.50 inches. Maximum of skull, 
2.00 inches....... floridana. 
2. About the same size, or rather larger. Tail about three-fourths the head and 
body. Color, brownish yellow above. Hind feet, 1.15-1.40 inches. mexicana. 
3. Eather larger than preceding. Tail little more than half the head and body. 
Color, uniform grayish slate above. Hind feet, 1.40.. micropus. 
b. Hind feet dushy ; tail nearly as long as head and body. 
4. Largest of slender-tailed species. Size and color of the Norway rat. Upper 
surface of metatarsus dusky ; toes alone white. Tail uniform dusky all round. 
Hind feet, 1.40-1.60....... fuscipes. 
B.— Tail densely hairy, (as in Myoxus.) 
5. Fur harsh, rigid ; the caudal vertebrae about as long as the trunk. Above, dark 
rusty brown; beneath, ashy white.. occidentalis. 
6. Fur soft; caudal vertebrae considerably shorter than the trunk. Above, yel¬ 
lowish plumbeous ; beneath, snowy white..... cinerea. 
NEOTOMA FLORID ANA, Say & Ord. 
Wood Rat. 
“ Mus floridana, Ord, Bull. Soc. Philom, 1818.” 
(Say & Ord) Say, in Long’s Exped. R. Mts. I, 1823, 54. 
Desmarest, Mammalogie, II, 1822, 307. 
Arvicola floridana, Harlan, F. Am. 1825, 141. 
Neotoma floridana, Say & Ord, J. A. N. Sc. Phila. IV, ii, 1825, 352 ; plate —.— Ib. Zool. Journal, It, 1826, 294 ; 
pi. x, fig. 1-4. (From preceding.) 
Isis, XX, 1827, 1035. 
Griffith’s Cuvier, III, 1827, 160 ; plate. 
