290 NELSONIA. 



two unequal lobes; second lower molar with one external and one 

 internal reentrant angle, separating the crown into two transverse 

 loops; the posterior occasionally exhibiting a second reentrant angle; 

 third lower molar with one internal reentrant angle, and a slight 

 external projection. The other molar teeth with patterns like those 

 of Neotoma and other allied genera. 



KEY TO TH SPECIES. 



A. Tail hairy, ears large, nearly naked. PAGE 



a. Above grayish brown and black N. neotomodon 290 



b. Above dark slate gray, washed with pale 



ochraceous N. goldmani 290 



294. neotomodon (Nclsonid), Merr., Proc. Biol. Soc. Wash., xi, 1897, 



p. 278. 

 ZACATECAS WOOD RAT. 



Type locality. Mountains near Plateado, State of Zacatecas, 

 Mexico. Altitude, 8,200 feet. 



Geogr. Distr. State of Zacatecas, Mexico. 



Genl. Char. Tail well haired; ears large, nearly naked. 



Color. Above grayish brown, lined with black on lower back; 

 sides pale fulvous; under parts white; orbital ring black; arms and 

 legs dusky to ankles exteriorly; upper lip and side of nose white; 

 tail above dusky, beneath white, tip white; hands and feet white. 



Measurements. Total length, 247; tail vertebras, 121; hind foot, 

 29. Skull: occipito-nasal length, 33; Hensel, 36; zygomatic width, 

 17; interorbital constriction, 5; length of nasals, 7; palatal length, 9; 

 length of upper tooth row, 6; length of mandible, 10. 



295. goldmani (Xelsonid), Merr., Proc. Biol. Soc. Wash., xvi, 1903, 



p. 80. 

 MT. TANCITARO WOOD RAT. 



Type locality. Mt. Tancitaro, State of Michoacan, Mexico. 



Genl. Char. Similar to .V. neotomodon, but darker and grayer; 

 tail well haired. Skull more angular, flatter between orbits ; vertical 

 lamella on anterior base of zygoma forming a spine; nasals narrower; 

 nostrils more constricted at base. 



Color. Above dark slate gray, washed with pale ochraceous; 

 beneath white, plumbeous under fur showing; tail above dusky, 

 beneath paler. Young dark slate. 



Measurements. Total length, 248; tail vertebrae, 122; hind 

 foot, 20. 



