6 OBSERVATIONS UPON 



and remove all doubts, is, that this jaw, like that of the Di- 

 delphis Prevostii, is formed of a single bone ; while in the 

 saurians, it is well known that each half is formed of five 

 osseous pieces. 



The inductions which have been drawn from the lobulated 

 character of the teeth in these animals, appear to me to prove 

 that this configuration has been greatly exaggerated. Let 

 us only examine the false molars of a carnivorous animal, 

 a panther for instance — and we perceive that they are also 

 formed of a middle tubercle, compressed and triangular, hav- 

 ing on each side a little "talon" or tubercle. There is nothing 

 more in the teeth of the Stonesfield fossil. This sort of pal- 

 mated appearance is not at all similar to the flattened and 

 triangular teeth of some of the saurians, which have, as in 

 the Iguanas, their edges notched in very fine regular indent- 

 ations. 



This comparison leads me back to the osseous fragment 

 possessed by Mr. Sykes. This jaw, belonging to the right 

 side, has its external surface visible ; its ascending ramus 

 and symphysary portion are wanting. We perceive in it nine 

 distinct teeth, and the socket for a tenth. The artist, who 

 was not an anatomist, has represented the teeth as with crowns 

 divided into lobes, to the number of five, and forming a sort 

 of "rosace", which never exists either in the Mammalia or Rep- 

 tilia. It appears to me that these organs have not been pro- 

 perly detached from their matrix, and that persons have been 

 led into error as to the palmated division of these teeth. 



Having thus given the reasons which prove to me that the 

 animal to which the fossil jaws discussed in this memoir have 

 belonged, must have been a mammal, let us examine to what 

 order it ought to be referred. 



I apprehend that what has led us from the truth has been 

 the comparison made between these fossil animals and the 

 common opossum (Didelphis Virginiana). We see, in fact, 

 in this animal, that the second false molar is much higher 

 than those next to it, and that it differs from them. But let 

 us take, as a point of comparison, the D. murina, which is a 

 small didelph of about the same size ; and we shall find the 

 resemblance more striking, and shall no longer wonder at the 

 affinity indicated by M. Cuvier. In this animal the false 

 molars are of the same height, and are equally pressed one 

 against another ; they are, like nearly all the false molars of 

 the true carnassiers, triangular, and have on each side a small 

 supplementary tubercle. The posterior molars, like those of 

 the fossil which I have in view, have two points, succeeded 

 by a small "talon," upon the outer edge, and three conical and 



