MAMMALIA OF STONESFIELD SLATE. 
347 
of Oxfordshire ought to be referred to the marsupial quad¬ 
rupeds, o*r to the ordinary placental series. Cuvier had long 
Fig. 340. Fig. 841. 
Part of lower jaw of Tupaia Tana. 
Twice natural size. 
Fig. 340. End view seen from behind, 
showing the very slight inflection 
of the angle at c. Fig. 341. Side 
view of same. 
Fig. 342. Fig. 343. 
Fig. 342. End view seen from behind, 
showing the inflection of the angle of 
the jaw, c, d. Fig. 343. Side view of 
same. 
ago pointed out a peculiarity in the form of the angular proc¬ 
ess (c, Figs. 342 and 343) of the lower jaw, as a character of 
the genus Didelphys^ and Professor Owen has since con¬ 
firmed the doctrine of its generality in the entire marsupial 
series. In all these pouched quadrupeds this process is turned 
inward, as at c, c?, Fig. 342, in the Brazilian opossum, whereas 
in the placental series, as at c. Figs. 340 and 341, there is an 
almost entire absence of such inflection. The Tupaia Tana 
of Sumatra has been selected by Mr. Waterhouse for this 
illustration, because the jaws of that small insectivorous 
quadruped bear a great resemblance to those of the Stones- 
Amphitherium Prevostii, Cnv. sp. Stonesfield Slate. Syn. Thylaco- 
therium Prevostii, Valenc. 
a. Goronoid process, b. Condyle, c. Angle of jaw. d. Double-fanged molars. 
field Amphitherium. By clearing away the matrix from the 
specimen of Amphitherium Prevostii here represented (Fig. 
344), Professor Owen ascertained that the angular process 
(c) bent inward in a slighter degree than in any of the known 
marsupialia; in short,*the inflection does not exceed that of 
the mole or hedgehog. This fact made him doubt whether 
