202 FOSSIL JAWS FROM STONESFIELD. 



C'est celle d'un petit carna,ssier dont les machelieres ressemblent beaucoup 

 a celles des sarigues ; mais il y a dix de ces dents en serie, nombre que ne 

 montre aucun carnassier connu." (Oss. Foss. 111. 349. note). It is to be 

 regretted that the particular data, with the exception of the number of 

 the teeth, on which Cuvier based his opinion, were not detailed; but he 

 must have been well aware that the grounds of his belief would be obvious, 

 on an inspection of the fossil, to every competent anatomist : it is also to 

 be regretted that he did not assign to the fossil a generic name, and thereby 

 have prevented much of the reasoning founded on the supposition that he 

 considered it to have belonged to a true Didelphys. 



" Mr. Owen then proceeded to describe the structure of the jaw ; and he 

 stated that having had in his possession two specimens of the Thylacothe- 

 rium Prevostii, belonging to Dr. Buckland, he has no hesitation in declar- 

 ing that their condition is such as to enable any anatomist, conversant with 

 the established generalizations in comparative osteology, to pronounce there- 

 from not only the class, but the more restricted group of animals to which 

 they have belonged. The specimens plainly reveal, first, a convex articular 

 condyle; secondly, a well-defined impression of what was once a broad, thin, 

 high, and slightly recurved, triangular, coronoid process, rising immediate- 

 ly 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: this impression also exhibits traces of the ridge leading forwards 

 from the condyle and the depression above it, which characterises the coro- 

 noid process of the zoophagous marsupials; thirdly, the angle of the jaw is 

 continued to the same extent below the condyle as the coronoid process 

 reaches above it, and its apex is continued backwards in the form of a pro- 

 cess ; fourthly, the parts above described form one continuous portion with 

 the horizontal ramus of the jaw, neither the articular condyle nor the coro- 

 noid being distinct pieces, as in reptiles. These are the characters, Mr. 

 Owen believes, on which Cuvier formed his opinion of the nature of the fos- 

 sil ; and they have arrested the attention of M. Valenciennes, in his endea- 

 vours to dissipate the doubts of M. de Blainville. 1 



" From the examination of a cast the latter, however, has been induced 

 to infer that there is no trace of a convex condyle, but in place thereof an 

 articular fissure, somewhat as in the jaws of fishes; that the teeth, instead 

 of being imbedded in sockets, have their fangs confluent with or anchylosed 

 to the substance of the jaws, and that the jaw itself presents evident traces 

 of the composite structure. 



" In answer to the first of these positions, Mr. Owen states that the por- 

 tion of the true condyle which remains in both the specimens of Thylaco- 

 therium examined by Cuvier and M. Valenciennes, clearly shows that the 

 condyle was convex, and not concave. It is situated a little above the le- 

 vel of the grinding surface of the teeth, and projects beyond the vertical 

 line dropped from the extremity of the coronoid process, but not to the 

 same extent as in the true Didelphys. In the specimen examined by M. 

 Valenciennes, the condyle corresponds in position with that of the jaw of 

 the Dasyurus rather than the Didelphys ; it is convex, as in mammiferous 

 animals, and not concave as in oviparous. The entire convex condyle ex- 

 ists in the specimen belonging to the other genus, Phascolotherium, now in 

 the British Museum, but formerly in the cabinet of Mr. Broderip. Mr. 

 Owen is of opinion that the entering angle or notch, either above or below 



i 'Comptes Rendus,' 1838; Second Semestre, No. 11, Sept. 10, p. 527 et 



