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 Trigonia, but living Terebratula exist, and 

 the latter abundantly, in the Australian seas, yielding 

 food to the Cestmcion, as their extinct analogues doubt- 

 less did to the allied cartilaginous fishes, called Acrodi, 

 Psammodi, &c. Araucarise 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 1 s surface, 

 which has been superseded in our hemisphere by other 

 strata and a higher type of Mammalian organization. 



