DISTRIBUTION OF MAMMALS IN TIME. 



S 6l 



occurs in Europe, has been found the jaw of a small Mammal, 

 which is probably Marsupial, and has been named Droma- 

 therium (fig. 213). 



Fig. 213. Lower jaw of Dromatherium sylvestre (after Emmons). From rocks, 

 supposed to be of Triassic age, in North CaroHna. 



In the next mammaliferous horizon, however namely, that 

 of the Stonesfield Slate in the Lower Oolites there is no doubt 

 but that some of the Mammalian remains, if not all, belong to 

 small Marsupials (fig. 214). From this horizon the two genera 

 Phascolotherium2&&Amphithtrium> are almost certainly referable 

 to the Marsupialia; the latter seeming to be most nearly related 

 to the living Myrmecobius, whilst the former finds its nearest 

 living ally in the Opossums of America. The Stereognathus of 

 the Stonesfield Slate is in a doubtful position. It may have 

 been Marsupial, but, upon the whole, Professor Owen is inclined 

 to believe that it was placental, hoofed, and herbivorous. 



( cfe 



Fig. 214. Oolitic Mammals, natural size. i. Lower jaw and teeth of Phascolotheriunt / 

 2. of Triconodon ; 3. of Amphitherium ; 4. of Plagiaulax. 



With the occurrence of small Marsupials in England within 

 the Oolitic period, it is interesting to notice how the fauna of 

 that time approached in other respects to that now inhabiting 

 Australia. At the present day, Australia is almost wholly 

 tenanted by Marsupials ; upon its land-surface flourish Arau- 

 carice and Cycadaceous plants, and in its seas swims the Port- 

 Jackson Shark ( Cestracion Philippt) ; whilst the Molluscan 

 genus Trigonia is nowadays exclusively confined to the Aus- 

 tralian coasts. In England at the time of the deposition of the 

 Stonesfield Slate, we must have had a fauna and flora very 

 closely resembling what we now see in Australia. The small 



VOL. II. 2 N 



