MR. E. T. BENNETT ON THE CHINCHILLID. 55 
cylindrical ; and they are all, except the smaller terminal ones, furnished with V-shaped 
apophyses. ‘The sternum is composed of six bony pieces, in addition to the xiphoid car- 
tilage ; of these the manubrium is long, broadly expanded in its anterior half, and some- 
what paddle-shaped ; the penultimate is by much the smallest. Seven pairs of the ribs 
are directly articulated with the sternum. 
The clavicle is perfect, but slender and slightly curved ; and the scapula small, with 
the spine nearly median and little elevated posteriorly, but terminating in a long acro- 
mion, the free portion of the spine being nearly equal to the whole attached length. On the 
outer and upper part of the humerus there is a strongly marked deltoid process, from which 
aridge is continued downwards. The olecranon is large; and the radius and ulna, although 
distinct, are so closely applied to each other at their carpal extremity, as to appear an- 
chylosed for one half of their length in Chinchilla, and one fourth in Lagotis. The four 
fingers of Lagotis are composed of three phalanges, additional to the metacarpal bones, 
and there is not the smallest vestige of a thumb. In Chinchilla the phalanges of the cor- 
responding fingers are formed upon the same plan ; and the thumb has two distinct pha- 
langes in addition to its proper metacarpal bone. The pelvis is long and narrow, the criste 
of the ta being much extended forwards, and the great size of the obturator foramina 
giving rise to a similar projection of the ischia backwards. The femur is straight and 
cylindrical ; it is half as long again as the humerus. The tibia is twice the length of 
the radius. The fibula is complete and detached, but very slender. The length of the 
soles of the hinder feet, from the calcaneum to the tip of the longest toe, is nearly three 
times that of the anterior from the carpal articulation outwards. The whole length of 
the free portion of the posterior limbs is consequently about double that of the anterior. 
The metatarsal bones are four in number ; and each toe has three phalanges, the outer- 
most of the four just reaching the base of the next adjoining toe. 
The comparative measurements of the bones in the two animals are as follow :— 



Lagotis. Chinchilla. 
No. Ft In. No. Ft In. 
Length of the head . . . ...., 3:2 2°3 
vertebre, cervical 7 . . 1:3 ES wae 8 
dorsal 12 . . 3:3 1S aa ae 2°3 
lumbar) (70252 3°6 Gra 2-2, 
sacral GOs 8 Dyas: 5 
caudal 27 . . 1 O4 Poe re: 6° 
eval Tenet es bes taein atx 06 ee | 
Renpthofitherskulll: .50 ene ey ye eal ou - 32 2:3 
Breadth of do. at the meatus auditor. M5 le2 
sygomata . . . 1:7 1:2 
