G) 
M. Valenciennes in his endeavours to dissipate the doubts of M. de 
Blainville*. 
From the examination of a cast, the latter, however, has been in- 
duced 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 
portion of the true condyle which remains in both the specimens of 
Thylacotherium examined” by Cuvier and M. Valenciennes, clearly 
shows that the condyle was convex, and not concave. It is situated 
a little above the level of the grinding surface of the teeth, and pro- 
jects beyond the vertical line, dropped from the extremity of the coro- 
noid process, but not to the same extent as in the true Didelphys. 
In the specimen examined by M. Valenciennes, the condyle corre- 
sponds 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 exists 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 the true articular condyle, has been mistaken for “‘ une 
sorte d’échancrure articulaire, un peu comme dans les poissons.”’ 
The specimen of the half-jaw of the Thylacothere examined by 
M. Valenciennes, like that which was transmitted to Cuvier, presents 
the inner surface to the observer, and exhibits both the orifice of the 
dental canal and the symphysis in a perfect state. The foramen in the 
fossil is situated relatively more forward than in the recent Opossum 
and Dasyure, or in the Placental Insectivora, but has the same place 
as in the marsupial genus Hypsiprymnus. The symphysis is long and 
narrow, and is continued forward in the same line with the gently 
convex inferior margin of the jaw, which thus tapers gradually to a 
pointed anterior extremity, precisely as in the jaws of the Marsupial 
Insectivora. In the relative length of the symphysis, its form and 
position, the jaw of the Thylacotherium precisely corresponds with 
that of the Didelphys. 
In addition, however, to these proofs of the mammiferous nature 
of the Stonesfield remains, and in part of their having belonged to 
Marsupialia, Mr. Owen stated that the jaws exhibit a character 
hitherto unnoticed by the able anatomists who have written respect- 
ing them, but which, if co-existent with a convex condyle, would 
serve to prove the marsupial nature of a fossil, though all the teeth 
were wanting. 
In recent marsupials the angle of the jaw is elongated and bent 
inwards in the form of a process, varying in shape and development 
in different genera. In looking, therefore, directly upon the infe- 
rior margin of the marsupial jaw, we see in place of the edge of a 
* Comptes Rendus, 1838; Second Semestre, No. 11, Sept. 10, p. 527 
et seq. 
