640 Doubts respecting 



M. Constant Prevost, during a visit to England in 1825, 

 undertaken for the purpose of geological research, made it 

 one of his principal objects to visit Stonesfield; and even 

 during his stay at Oxford he sent to M. G. Cuvier a drawing 

 very carefully executed, of the half jaw possessed by the Ox- 

 ford Museum, which Dr. Buckland had immediately submit- 

 ted to his inspection. M. Cuvier, who had at first only ven- 

 tured to remark, — with regard to the bones of reptiles col- 

 lected at Stonesfield, — "among these innumerable marine 

 fossils, there are sometimes long bones, which appear to me 

 to belong to birds of the order of waders ; and there have 

 even been, as I am assured, two fragments of a lower jaw, 

 which, judging from a hasty inspection made at Oxford in 

 1818, appeared to me that of a Didelphis" — was now so 

 confirmed in his first idea or attempt at classification, that he 

 even proposed designating the fossil by the name of Didel- 

 phis Prevostii. Indeed on this subject we may refer to the 

 very text of the note which Cuvier has given in page 349 of 

 the 2nd part of Vol. v. of his c Recherches sur les Ossements 

 Fossiles,' published in 1826. — "M. C. Prevost, who is at 

 present travelling in England, has just sent me a sketch of 

 one of these jaws, which confirms the impression I had re- 

 ceived from their first inspection. It is that of a small carni- 

 vorous animal, the grinders of which very much resemble 

 those of the opossums, but there are ten teeth in a row, a num- 

 ber exceeding that of any of the known order of carnassiers. 

 Under all circumstances, if this animal be positively from the 

 Stonesfield slate, it is an exception to the rule, otherwise 

 so general, that beds of that age do not contain the remains 

 of Mammalia.'''' 



We see from this passage that the doubt related, not to the 

 recognition of the fossil as referable to an animal so much 

 resembling an opossum that Cuvier inserted it in that genus, 

 — but to the certainty of its position in the Stonesfield slate. 



In this point of view it was that M. Prevost, upon his re- 

 turn from England, introduced the question in a report made 

 to the Philomathic Society, upon a memoir of M. Denoyers 

 published in the c Annales des Sciences Naturelles for 1825. 

 After a rather detailed description of the portion of jaw un- 

 der observation, accompanied by a drawing twice the natural 

 size, made with the greatest care by the aid of a magnifier, 

 M. Prevost, without any preconceived idea, arrives at the con- 

 clusion (based almost exclusively upon the existence^of dou- 

 ble roots to the teeth, which I had myself pointed out), that 

 this jaw belonged to one of the insectivorous marsupials, ap- 

 parently having some affinity to the opossums, but which 



