Geological Society of London. 181 



siosaiirs, and the like, are inserted in distinct sockets ; but then they 

 have not double fan^s. The Basilosaums was supposed to be a saurian 

 with double-fanged tceth^but that exception was disposed of afterwards. 

 And as there are thus saurians whicli trench upon the characters of mam- 

 malsj there are mammals in ^Yhich some of the above characters are want- 

 ing : thus the condj-le is slightly or not at all convex in the Ruminantia ; 

 there is no elevated coronoid process in the Edentata ; the Dolphin and 

 Porpoise have not multicuspid teeth ; the Armadillo has not varied forms 

 of teethj nor has it double fangs to its teeth, which also tlie fossil Mega- 

 therium has not. Still, upon the whole, the above appears to be the gene- 

 ral line of distinction. Even if one or two of the above nine marks were 

 wanting to prove the animal a mammal, still if the great majority of them 

 were present, our judgment could not but be decided by the preponde- 

 rance of characters. But if all the above characters of mammals are pre- 

 sent, and all those of saurians absent, it seems to be a wanton scepticism 

 to doubt that the animal was realh- warm-blooded. 



" Now it was asserted by Jlr Owen, who brought this subject before 

 us, that this is the case ; that all the characters which I have enumerated 

 above exist in the Stonesfield jaws. If we satisfy ourselves that this is 

 ilie case, I do not see how we can avoid assenting to his opinion, — that 

 tiie animal belonged to the class jMammalia. 



" Every such question'of classification must resolve itself into two ; that 

 of the value, and that of the existence of the characters. If we assent to Mr 

 Owen in his view of the former, we are then led to consider the latter. 



" M. de Blainville, at least in his first examination, had laboured under 

 the disadvantage of formingthis judgments from casts and drawings only of 

 the Stonesfield bones. Under these circumstances, he had denied seve- 

 ral of the above characters ; he had held that the teeth in the Thylaco- 

 llieriura are uniform ; and that they are confluent with the jaw ; and that 

 ;he jaw is compound. These statements Mr Owen, resting upon a care- 

 ful examination of the specimens, contradicts. The assertion of the com- 

 ])ound nature of the jaw is occasioned by a groove near the lower margin 

 of the jaw, which, however, is not so situated as to represent the saurian 

 .viitureSj but is completely explained by supposing it to be a vascular 

 canal, such as exist in the Wombat, Didelphys, Opossum, and similar 

 animals. 



" Another specimen, at that time the property of Mr Broderip, but 

 ii:iw very properly placed in the British Museum, exhibits a jaw similar 

 indeed to the Tliylaeothere, but belonging to a different genus ; and to 

 I his species Mr Owen has given the name Phascolotherium Buck/andi. 

 But these generic names imply that the animals are pouched animals ; 

 and in addition to the reasons which led Cuvier to this opinion, Mr 

 Owen has noticed in the fossils an inflection of the lower edge of the jaw, 

 which, so far as has been hitherto observed, occurs in Marsupials, and in 

 tliem .alone. 



" As if this question had been destined to be settled at this time, the 



