GENUS DIPODOMYS.— Gray. 
DENTAL FORMULA. 
Incisive \ ; Canine ^ ; Molar ^ = 20. 
The incisors are of moderate length, rather weak, narrow, compressed, 
and curved inwards. In the upper jaw the first three molars are largest, 
the fourth a little smaller ; in the lower jaw the molars are alike. The 
molars have rounded cutting edges. 
Nose and head, of moderate size ; sacs or pouches opening on the cheeks 
back of the mouth ; fore feet, rather short, furnished with four toes and the 
rudiment of a thumb, covered by a blunt nail ; hind legs very long, termi- 
nated by four toes on each foot ; toes, each with a distinct metatarsus ; 
tail, very long ; mammce, four — two abdominal and two pectoral. 
Habits, semi-nocturnal ; food, seeds, roots, and grasses. 
There is only one species belonging to this genus known. The generic 
name is derived from Siirovg, dipous, two footed, and mus, a mouse. 
DIPODOMYS PHILLIPPSII.— Gray. 
Pouched Jerboa Mouse. 
PLATE CXXX.— Males. 
D. Magmtudine prope Tamise Lysteri et forma Dipodum ; caudal 
corpore et capite conjunctum multo longiorc ; sacculis buccalibus cxternis 
apertis ; colore, supra fulvo, infra albo. 
CHARACTERS. 
Nearly the size of the common ground squirrel (Tamias Lysteri) ; shaped 
like the jerboas ; tail , much longer than the body ; cheek pouches, opening 
externally ; colour, light brown above, white beneath. 
SYNONYME. 
Dipodomys Phillippsii. Gray, Ann. and Mag. Nat. Hist., vol. vii. p. 521. 1840., 
YOL. ITT. — 18 
