56 MR. E. T. BENNETT ON THE CHINCHILLIDA. 




Lagotis. Chinchilla. 
In, In. 
Distance between the orbits above ! ‘8 “45 
Diastematic distance, upper jaw 73) 5 
lower jaw oa 4 
Length of molar series in each jaw af 5 
mastoid process, or inferior di- 
vision of the tympanic cells . . . 6 7 
Greatest breadth of do. . . . “45 5 
Length of the lower jaw fradaine we 
CELL) 4's vastus’ Kaecpeass daasl soak memel ies: 275) 18 
Height of the coronoid process. . . . 8 7 
Length of the clavicle . . . . . . “9 6 
scapula) BOM): TANT Sem): 1:8 12 
[imeris VIM). FE 2° 1:2 
TODS) ANITA, ODA Mi lee Oe: 19 1:2 
uma. . 2:4 16 
fore-foot to the ~" af the 
middle fingeene¥ IPT. AU, Mars 2 Led: “9 
Length of the pelvis from the crista alu to 
CHENPUUCTATSCHUUMN Pe tn i 33 22 
Greatest breadth ofdo. . . . .. . leg 1:2 
Ieeneth of the femur 7 3. t . 3 Leg 
Ue ee ; 38 23 
hind-foot from ke bate 
neum to the end of the longest toe . 36 2:2 
With the animals just described Lagostomus corresponds in the general composition 
of its skeleton, and even in the form and proportion of most of the separate bones. It 
is still larger in size than Lagotis ; and the figure accompanying Mr. Brookes’s de- 
scription exhibits several very striking differences in the form of the cranium. As, 
however, the details of that important part are not there made out with sufficient clear- 
ness, and I possess no notes relative to its peculiarities, I can do no more than refer to 
the plate itself. ‘The number of ribs on each side, and consequently of the dorsal ver- 
tebre, was twelve, and that of the lumbar vertebre seven, corresponding in these par- 
1 This and the zygomatic breadth depend in Lagotis on the less oblique and more lateral position of the eyes, 
the orbits of which have their margins also much expanded, a structure perhaps connected with more nocturnal 
habits. 
