124 MAMMALS. 



ported to have been found in the secondary greensand of New Jersey, in North America. Both are 

 attended with very grave doubt, the specimen of the tooth of the Seal having gone a-missing ; and 

 the authentication of the locality of the other having been questioned, apparently on good grounds. 

 The former was described and figured by Dr. Leidy under the name of Stenorhynchus vetus, not 

 from personal inspection but from a drawing of Conrad's.* The fossil was found by Samuel R. 

 Wetherill, Esq., in the greensand, a mile and a half south-east of Burlington. Sir Chas. Lyellf tells 

 us that that gentleman related to him and Mr. Conrad, in 1853, the circimistances under which he 

 met with it, associated with Ammonites placenta, Ammonites Delawarensis, Trigonia thoracica, &c. ; and he 

 adds that although the tooth had been mislaid, it was not so imtil it had excited much interest, and 

 been carefully examined by good zoologists. The doubt in the case of the cetacean applied to the 

 locality where it was found, not to the detennination. Here it is the reverse. There seems no 

 reason to doubt that the tooth was found where Mr. Wetherill said it was, nor is there any question 

 here of misplaced labels, but there is certainly room for doubting its detennination, because we see 

 where and how an error might easily enough have arisen. In the first place, it is referred to a 

 living genus of mammals, and wo know of no genus which has subsisted through so many cycles. 

 The presumption is therefore against it on that score. In 

 the next place, there is a certain resemblance between the 

 teeth of Sharks and some Seals, and it is precisely in 

 the genus Stenorhynchus that the resemblance is most 

 K , J „,.,,.„. I marked. Figs. 1 and 2 represent the teeth of Sharks .,. , , , „ „ „, ,. 



Figs. 1 and 2.— Shark s Teeth, ° ^ Figs. 3 and 4. — Seals Teeth. 



from the chalk ; and figs. 3 and 4, teeth of the living Stenorhynchus leptonyx. Those of which 

 I speak both have the molars compressed, with the crown divided into three conical spilies, of 

 which the middle one is the largest. It is possible, therefore, that the supposed Seal's tooth may 

 have been a very much rubbed and worn Shark's tooth ; and although LyeU saj'S it was care- 

 fidly examined by good zoologists, the only one of known competence whom he mentions as 

 having had to do with it is Dr. Leidy, who did not see it, but described it from a drawing. 



The objections to the supposed mesozoic Seal's tooth, therefore, appear to be too well foimded 

 to require us to devote much time to a speculation founded upon its authenticity. The next 

 most ancient deposit in which the remains of Seals have been found is the miocene. Assuming, 

 then, that the genus dates from these more recent beds, we may adopt, as a starting-point, 

 that the Seals have descended from terrestrial carnivora. From which then ? From animals that 

 are already half aquatic, or from others that are not so ? Our first inclination certainly would 

 be to look to species which had already performed the journey half-way from terrestrial to ma- 

 rine. There arc two other carnivora which are in this position ; — the Otter and the Polar Bear are 

 amphibious, and wo can easily conceive of either nourishing and bringing up an aquatic family. The 

 claims of the Otter, although it bears some slight facial resemblance to a Seal, need not occupy so 

 long. It is a modified Polecat, and to develope it into a Seal, we should require not merely to alter 

 its habits of life, but to eSect other modifications in its structure and, what also appears to me of 

 importance in these questions, in its size. Size is an element in determining affinities which, although 

 tacitly allowed a good deal of weight, is, I think, scarcely sufiiciently recognised. As a rule giants 

 do not beget dwarfs nor dwarfs giants. We would rather go to Brobdiguag than to Lilliput to look 



* See " Proceedings of the Academy of Natural Sciences of Philadelphia," 1853, p. 377. 

 t Lyell's " Elements of Geology," sixth edition, London, 1665, p. 3o6. 



