PHASCOLOTHERIUM. 69 
conversant with the details of Comparative Anatomy. The 
cumulative evidence of the true nature of the Stonesfield 
fossils, afforded by the shape of the condyle, coronoid pro- 
cess, angle of the jaw, different kinds of teeth, with the 
shape of their crowns, double fangs, and implantation in 
sockets, reposes on structures which cannot be due to acci- 
dent, while those which favour the evidence of the com- 
pound structure of the jaw may arise from accidental cir- 
cumstances. 
The close approximation of the Phascolotherium to mar- 
supial genera now confined to New South Wales and Van 
Dieman’s Land, leads us to reflect upon the interesting 
correspondence between other organic remains of the Bri- 
tish oolite, and other existing forms now confined to the 
Australian continent and adjoining seas. Here, for ex- 
ample, swims the Cestracion, which has given the key to 
the nature of the ‘ palates’ from our oolite, now recognized as 
the teeth of congeneric gigantic forms of cartilaginous fishes. 
Mr. Broderip, in his memoir above quoted, observes, ‘‘ that 
it may not be uninteresting to note, that a recent species 
of Trigonia has very lately been discovered on the coast of 
Australia, that land of marsupial animals. Our specimen 
lies imbedded with a number of fossil shells of that genus.” 
Not only Trigonie, but living Terebratule exist, and 
the latter abundantly, in the Australian seas, yielding 
food to the Cestracion, as their extinct analogues doubt- 
less did to the allied cartilaginous fishes, called Acrodz, 
Psammodi, &ce. Araucarie and cycadeous plants, like- 
wise, flourish on the Australian continent, where mar- 
supial quadrupeds abound, and thus appear to complete 
a picture of an ancient condition of the earth’s surface, 
which has been superseded im our hemisphere by other 
strata and a higher type of Mammalian organization. 
