104 Mr. Bnooxzs on a new Genus of the Order Rodentia. 
Feet. Inches. 
From the atlas to the tuber ischii- . . . . . 1 O8 
crista ilii to the tuber ischii . . . 0 4 
Length of the fore extremity from the head of the S 
os brachii to the end of the longest nail . . O 6 
from the head of the os brachii to the ex- 
ternal condyle. 3: spao 0... 21 
from the end of the olecranon do that m 
the longest las = Oa 
of the hinder extremity . . . . . . 1 OQ 
from the trochanter major to the lower 
portion of the external condyle of the femur O — 3i 
from the upper surface of the tibia along ` 
the fibula to the malleolus externus . . . O 4 
from the end of the os calcis to the ex- 
treme end of the middle toe. . . . . dQ 44 
The occipital diameter of the cranium of the Lagostomus is 
1 inch and &ths, and its diameter between the ascending por- 
tions of the zygoma 1 inch and &ths. The corresponding mea- 
surements in the Dipus are respectively zths and 4ths of an 
inch. 
EXPLANATION OF TAB. IX. 
Fig. a. Lagostomus trichodactylus, ) 
esie ee Half the Natural size. 
c. Upper jaw, 
d. Under jaw, _ J 
. €. Crown of the second molar tooth of the ? 
left side of the lower jaw, 
f. Ditto of the last molar tooth of the right 
side of the upper jaw, J 
> Natural size. 
VII. De- 
