654 Doubts respecting the Fossil Jaws of Stonesfield. 



carnivorous mammal ; we can neither hesitate to admit thai 

 if this Basilosaurus be a reptile, which fact appears placed 

 beyond doubtby the form of the vertebra, humerus, &c, it is 

 more than probable that it is an animal of the same kind as 

 that found at Stonesfield. 



The existence therefore of fossil bones belonging to an ani- 

 mal of the class Mammalia, even aquatic, is not yet added to 

 our knowledge of the science ; the supposed didelph of Stones- 

 field not belonging to this class. 



For the rest, if the discussion upon which we have now en- 

 tered has not rendered the demonstration perfectly convincing 

 to every one, we may at least hope that its subsequent effect 

 will be to direct new investigations on the part of the skilful 

 observers who have at their disposal the only two specimens 

 of this fossil known at the present day, and in the end to 

 furnish new topics of argument for or against an opinion till 

 now admitted without sufficient examination, and consequent- 

 ly not demonstrated. We should indeed, in order to assist 

 our doubts upon the subject, invoke the opinion of M.M. Mey- 

 er, Grant, and Agassiz, who appear to agree with us in think- 

 ing that the Stonesfield fossil does not belong to a mamma- 

 liferous animal. 



Meanwhile, in the present state of our information, it ap- 

 pears to me that we are authorized in drawing the following 

 conclusions. — 



1st. The two solitary fragments found at Stonesfield and 

 referred to the genus Didelphis of the class Mammalia, have 

 none of the characters of animals of this class, and certainly 

 ought not to be arranged among them. 



2nd. Neither can they be referred to an insectivorous mo- 

 nodelph allied to the Tupaia or tenrecs. 



3rd. If we deem ourselves justified in regarding them as of 

 the class Mammalia, the molar portion of their dental sys- 

 tem brings them nearer to the family of the seals than to any 

 other. 



4th. But it is infinitely more probable, from analogy with 

 what we know of the Basilosaurus found in America, in a for- 

 mation likewise secondary, that they ought to be referred to a 

 genus of the suborder of saurians. 



5th. That in any case they must be distinguished by a dif- 

 ferent generic name, for which purpose we propose that of 

 Amphitherium, as indicating their ambiguous nature. 



Lastly ; the existence of the remains of mammals anterior 

 to the formation of tertiary strata, is not at all proved by the 

 Stonesfield fossils on which we have now treated, although we 

 are far from asserting that mammals were not in existence 

 during the secondary period. 



