290 NELSONIA. 
two unequal lobes; second lower molar with one external and one 
internal re*ntrant 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 THE SPECHES: 
A. Tail hairy, ears large, nearly naked. PAGE 
ay Abovervsrayish= brown andy bilackec. se eeeeee N. neotomodon 290 
b. Above dark slate gray, washed with pale 
ochraceous...) .. SS ace ee eee N. goldmant 290 
294. neotomodon (Nelsonia), Merr., Proc. Biol. Soc. Wash., x1, 1897, 
Puzo: 
ZACATECAS Woop 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 vertebre, 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, ro. 
295. goldmani (Nelsonia), Merr., Proc. Biol. Soc. Wash., XVI, 1903, 
p. So. 
Mr. TANCITARO Woop Rat. 
Type locality. Mt. Tancitaro, State of Michoacan, Mexico. 
Genl. Char. Similar to N. 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 vertebre, 122; hind 
foot, 20. 
