54 NEW DOUBTS RESPECTING 



and is to a certain degree correct when we apply it to known 

 animals, or to such as differ but little from them, becomes 

 strained, and even quite fallacious, when the forms in ques- 

 tion are more or less isolated, whether recent or fossil ; this 

 will be placed beyond doubt in the continuation oi' my great 

 paleontological work. 



M. De Blainville then passes on to the detailed description of three 

 portions of jaw, which form fresh elements in the solution of the ques- 

 tion. 



With respect to the first, the basis of the Did. Prevostii, of 

 which he has been able to form a much more correct idea 

 from the cast, and one very different to that derived from very 

 inaccurate sketches, especially that given by M. Prevost, — 

 he alludes chiefly to there being no trace of a condyle, but ra- 

 ther a sort of articular fossa, something like that in fishes ; he 

 insists upon the presence of a lower marginal ridge, {sillori), 

 and he observes that the teeth, which are far from displaying 

 that regularity of disposition indicated by the figures which 

 have been mentioned, have the summit of their roots adher- 

 ent to, and continuous with, the substance of the jaw. 



Respecting the second portion of jaw which is now for the 

 first time introduced in the discussion, and which, while it is 

 more perfect with regard to the bone, is much less so as re- 

 spects the dental system, — M. de Blainville thinks, in oppo- 

 sition to what was said of it by M. Valenciennes, who looked 

 upon it as the inner side, that it is also a ramus of the right 

 side, with its external aspect visible; and in proof of his 

 opinion he points out the general curve of the horizontal por- 

 tion longitudinally, and its declension towards the dental 

 line ; the existence of a "fosse masstterienne" and of an an- 

 gular process, which is evidently convex on the free side and 

 bent back on the adherent one ; and finally, the existence of 

 the same ridge (sillon) observed in the preceding piece. He 

 does not admit the orifice of the dental canal noticed by M. 

 Valenciennes as a small circular foramen, situated at the point 

 of junction of the fosse massetgrienne with the horizontal 

 branch ; M. de Blainville supposing that this appearance, 

 which is so evident in the drawing, is owing to some defect 

 in the colouring, since there exists no trace of it in the sul- 

 phur impression, nor upon the plaster cast. Neither does 

 he admit the symphysis described by M. Valenciennes, any 

 more than an articular condyle, nor even a coronoid process, 

 clearly as it appears terminated in the figured fragment, be- 

 cause nothing similar shows itself in the sulphur impression. 



Finally, with respect to the third piece, consisting of a de- 

 sign carefully executed, which he has merely seen for a mo- 



