ON BRITISH FOSSIL MAMMALIA. 59 



against the fossils in question belonging to fishes, he would rather have been 

 led to suppose that they might have been the remains of an animal of that 

 class. 



With respect to the term ' amphibious,' in M. de Blainville's conclusion, 

 this has reference to a later opinion expressed by M. Agassiz*, who, admit- 

 ting the Stonesfield fossils to be certainly those of mammals, rejects them 

 from the marsupial and insectivorous orders, observing that " each separate 

 tooth resembles the greater part of those of seals, near which group (am- 

 phibious Carnivora) the animal to which the jaws belonged should form a 

 distinct genus. In fact," adds M. Agassiz, " the aspect of these fossil 

 fragments is so peculiar, that it draws our attention towards aquatic animals 

 rather than away from them." 



A mammiferous animal, not larger than the water-shrew, may manifest 

 aquatic habits, but can hardly be supposed to have been piscivorous, or to 

 have been endowed with instincts and an organisation like those of the 

 seals ; at all events it must be admitted, in the absence of any evidence of 

 the locomotive extremities, that such an affinity can only be matter of mere 

 conjecture ; which a close examination of the dental and maxillary characters 

 will show to have little probability. 



The fossil first discovered by Professor Buckland, and figured by the Pro- 

 fessor, by M. Prevost and myself, is the left ramus of a lower jaw wanting 

 the anterior extremity, containing ten of the molar teeth more or less broken, 

 and measuring ten lines in length. 



This specimen, however, plainly exhibits, — first, a convex articular con- 

 dyle ; secondly, an indubitable and well-defined impression of what was once 

 a broad, thin, high, and slightly recurved triangular coronoid process, 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 continued to nearly the 

 same extent below the condyle as the coronoid process reaches above it, and 

 with its apex continued 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. 

 As respects this last statement, it is to be observed that an inferior marginal 

 groove has been considered as evidence of the composite structure of the 

 jaw under consideration ; but there is no other mark that could be inter- 

 preted 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. 



M. de Blainville was led to suppose that there was no trace of a convex 

 condyle, but that in its place there existed an articular fissure, somewhat as 

 in the jaws of fishes ; that the teeth, instead of being imbedded in sockets, 

 had their fangs confluent with, or anchylosed to, the substance of the jaws ; 

 and that the jaw itself presented evident traces of a composite structure. 



The point, therefore, which first demanded the closest attention, was 

 the actual condition, in the Stonesfield fossils, of the articular or condyloid 

 process, in regard to which they give the same evidence. In the jaw examined 

 by Cuvier, in the second specimen of the same species examined by M. Va- 

 lenciennes, and in the lower jaw of another genus described and figured by 

 Mr. Broderip, a prominent convex articular condyle is more or less distinctly 

 revealed ; it is most entire and unequivocal in Mr. Broderip's specimen which 



* Neue Jahrbuch Mineral, und Geol. von Leonhard und Bronn, 1S35, iii. p. 185. 



