MAMMALS OF THK MEXICAN BOUNDARY. 4<W 



Subfamily .VK( ) T( > \I 1 N . K. 

 WOOD-RATS. 



Cranium not abruptly constricted in frontof brain case, which is 

 oval, gradually narrowing into orbit; orbital and temporal fossae indis- 

 tinguishable, without trace of separation; jugal wholly posterior, 

 forming insignificant part of zygoma and never reaching forward half- 

 way from squamosal root to maxillary plate; sagittal area elongated, 

 at least twice as long as broad; angular process of inaudible broadly 

 expanded vertically, inflected, not hamular, and never thickened at 

 end; infra-condylar notch high and shallow. * * * 



Molars prismatic, rooted or semirooted; the crowns flat, their sides 

 continuously invested with enamel which is folded on itself in such 

 manner as to present on each side of the tooth a series of salient loops, 

 alternating with reentrant angles or interspaces. ( Merriam.) 



Genus NEOTOMA Say and Ord (1825). 



Neotoma Say ;md Ord, Journ. Acad. Nat. Sci. Phila., VI, Pt. 2, 1825, pp. 345, 346, pis. 

 xxi and xxn. 



Type. — Mus floridana Ord, from eastern Florida. 



Generic characters. a — Crown of m 3 composed of two transverse 

 loops, (with the addition, in rare cases, of a narrow antero-external 

 loo})), never S-shaped; m t and 2 with middle loop undivided (reaching 

 completely across tooth) ; molar series relatively short ; condylar ramus 

 low and directed obliquely backward; coronoid notch horizontal or 

 nearly so [nearly vertical in Xenomys and Hodomys] : angle of mandi- 

 ble only moderately inflected; symphysis relatively short and 

 sloping strongly forward. (Merriam.) 



Subgenus NEOTOMA Say and Ord (1825). 

 Neotoma Say and Ord, Journ. Acad. Nat. Sci. I'hila., IV, Pt. 2, L825, pp. 345, 346, pis. 



XXI, XXII. 



Dentition. — I. jErf, M. ^3= L6. 



Type. — Mus Jtoridana Ord, from eastern Florida. 



Tail commonly round, scant-haired, and tapering, but in one 

 species moderately bushy; hind feet small or moderate 1 . 



Rostrum of moderate length, not more than one-third the length 

 of cranium; sagittal area usually rounded, the broadest part always 

 considerably anterior to plane of interparietal, whence the sides curve 

 gradually backward to interparietal shield: spheno-palatine vacui- 

 ties always open. (Merriam.) 



None of the thirteen species and subspecies of Neotoma inhabiting 



aThe characters here giveD are selected with reference to antithesis with Ptyssophorus, 

 Hodomys, and Xt nomys. 



