RODENTlA 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 slateabove. Hind feet, 1.40 micropus. 



b. Hind feet dusky ; 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., dnerea. 



&" . ...- 



NEOTOMA FLOEIDANA, Say & Ord. 



Wood Rat. 



" Musflmdana, ORD, Bull. Soc. Philom, 1818." 



(SAY & ORD) SAT, in Long's Exped. R. Mts. I, 1823, 54. 



DESMAREST, Mammalogie, II, 1822, 307. 

 Arvkola jloridana, HARLAN, F. Am. 1825, 141. 



Neotoma foridana, SAY & ORD, J. A. N. Sc. PhUa. IV, n, 1825, 352 ; plate . IB. Zool. Journal, II, 1825, 294 ; 

 pi. x, fig. 1-4. (From preceding.) 



Isis, XX, 1827, 1035. 



GRIFFITH'S Cuvier, III, 1827, 160 ; plate. 



