48 Mr. Owen on the Thylacotherium. 



fossil, described by Mr. Broderip*, and, since, liberally presented by that gentle- 

 man to the British Museum. 



And first, with reference to the condition of these specimens, I am justified in 

 stating, unequivocally, that each and all of them are sufficiently complete to furnish 

 grounds to any anatomist, conversant with the established generahzations in Com- 

 parative Osteology, for determining therefrom the class, if not also the more 

 restricted group of animals to which they have belonged. 



Cuvier, after an examination of one of the jaws from Dr. Buckland's collection, 

 pronounced " the animal to have been mammiferous, resembling an Opossum, although 

 of an extinct genus, and differing from all known Carnivorous Mammalia in having 

 ten molar teeth in a series in the lower jawf." It is to be regretted, that, with the 

 exception of the number of molar teeth, Cuvier did not specify the particulars on 

 which he founded his belief that the jaw in question represented a new but extinct 

 genus of mammalian, and probably marsupial quadrupeds. 



This specimen (PI. V. fig. 3), however, plainly exhibits, — first, a convex ar- 

 ticular condyle (a) ; — secondly, an indubitable and well-defined impression of what 

 was once a broad, thin, high, and slightly recurved triangular coronoid process (6), 

 rising immediately anterior to the condyle, having its basis extended over the whole 

 of the interspace between the condyle and the commencement of the molar series, 

 and having a vertical diameter equal to that of the horizontal ramus of the jaw 

 itself; — thirdly, the angle of the jaw (c) continued to nearly the same extent 

 below the condyle as the coronoid process reaches above it, and its apex is con- 

 tinued backwards in the form of a process ; — fourthly, the parts above-described 

 forming one continuous portion with the horizontal ramus of the jaw, which is not 

 compounded of three or four distinct pieces. It is true, with respect to the last 

 proposition, that an inferior marginal groove (d) has been considered as evidence 

 of the composite structure of the jaw under consideration ; but there is no other 

 mark that could be interpreted as an indication of this reptilian structure, whilst 

 a similar groove characterizes the lower jaw of the marsupial Myrmecobius and 

 Wombat, and of some large species of Sorex. 



Now these points, w^hich may be presumed to have influenced Cuvier in form- 

 ing his opinion of the nature of the fossil in question, are precisely those which 

 arrested the attention of M. Valenciennes, when he examined the fossil itself, and 

 which he has ably advanced in his endeavour to dissipate the doubts expressed by 

 M. de Blainville. 



Whence then, it may be asked, is the necessity of again describing these appear- 

 ances, and of again urging their importance as evidence of the mammiferous na- 

 ture of the Stonesfield jaw ? It arises from the circumstance that the Professor of 



» Zoological Journal, vol. iii. p. 409, PI. XI. 1828. f Loc. cit. p. 409. 



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