118 Merriam — American Wood Raf.<^. 



Kostrum of moilerate length, never more tluin one-third tlie length 

 of ciimium ; sagittal area usually rounded, the broadest part always con- 

 siderably anterior to plane of interparietal, whence the sides curve gradually 

 backward to interparietal shield ; spheno-palatine vacuties always open. 



(1) Neotoma leucodon group. — Neotoma leucodon, laHfrons, micro- 

 pus, hailcyi, jioridann and 'pcii.iisyJvniii.ca form a fairly well cir- 

 cumscribed group, differing from the other subdivisions of the 

 genus in having the frontals abruptly spreading and flattened 

 immediately behind the intcrorbital constriction, the orbital mar- 

 gins upturned and pinched in, almost forming a bead; the nasal 

 bones short and cuneate, tapering evenly to a dull point behind ; 

 the postpalatal notch moderately or broadly excavated (moder- 

 ately in leucodon, very broadly in floridana) ; the upper molar 

 series very much broader anteriorly than posteriorly (ni ^ nearly 

 h broader than m -) ; m ^ comprising three transverse loops, the 

 anterior of which is l)ut slightly indented by the antero-internal 

 sulcus — never divided by the deepening of this sulcus as in the 

 riicxirdiia series; color of teeth white or nearly white (except in 

 jliiridiiiKt, Avliich is an aberrant member of the group*). N. 

 pennsylvci.nica has certain primitive characters not shared by the 

 others, and is more nearly intermediate between the subgenera 

 Neotoma and Teommia than any known living species. The 

 group inhabits the Lower and Upper Sonoran Zones from 

 Perote in Vera Cruz and Berriozabal in Zacatecas, northward to 

 southern South Dakota. 



(2) Neotoma ■me.ricana grouj). — Neotoma me.rieana'f, pinetorum, 

 orizabcT. teiimceiiuUt, fuiviveiiter, fedhix and ft(^<cipe--i form a group of 

 closely allied species agreeing in certain important cranial char- 

 acters whereby they differ from all the other subdivisions of the 

 genus. N fuscipesX and fedlax are somewhat aberrant members 

 of the series. Neotoma torqnata Ward probably belongs here also. 

 The group seems to occupy a midway position in the genus, lack- 

 ing the more specialized characters that distinguish the others. 



*Iii most species of Neotoma the osteodentiiie is dark and the reentrant angles are 

 filled with a blackish substance. 



fOne subspecies oi viexicana is here recognized : N. m ex tear: a biillata from the Santa 

 Catalina Mts. in Arizona. 



I'i'he sub.species oi fitscipes here recognized are vtacrotis Thomas from the southern 

 coast region of California; streatori from the western slope of the Sierra Nevada and 

 adjacent parts of the upper Sacramento Valley, and dispar from the ea.st foot of the 

 Sierra along the western edge of the Mohave Desert region. N. monochroura Rhoads 

 and N. splendens True seem to be tj'pical fiiscipes, and N. niacrolis simplex an inter- 

 grade. 



