MAMMALS OP THE MEXICAN BOUJSTDART. 467 



Subfamily liTHlOTOIHITir^. 

 ■WOOD-RATS, 



Cranium not abruptly constricted in front of brain case, which is 

 oval, gradually narrowing into orbit; orbital and temporal fossa3 indis- 

 tinguishable, without trace of separation; jugal wholly posterior, 

 forniing 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 mandible 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 and Obd, Journ. Acad. Nat. Sci. Phila., VI, Pt. 2, 1825, pp.-345, 346, pis. 

 XXI and xxii. 



Type. — Mus floridana Ord, from eastern Florida. 



Generic characters. " — Crown of m^ composed of two transverse 

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

 loop), never S-shaped; m^ and j 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 (182S). 

 Neotoma Say and Ord, Joum. Acad. Nat. Sci. Phila., IV, Pt. 2, 1825, pp. 345, 346, pis. 



XXI, XXII. 



Dentition. — I. j^; M. 3^3= 16. 



Type. — Mus floridana Ord, from eastern Florida. 



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

 species moderately bushy; hind feet small or moderate. 



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 



oThe characters here given are selected with reference to antithesis with PtyssopTiorus, 

 Hodomys, and Xenomys. 



