Aug. 1833. 



FOSSIL QUADRUPEDS. 



97 



also part of the head of a Ctenomys ; the species being dif- 

 ferent from the Tucutuco^ but with a close general resem- 

 blance. 



The remains at Punta Alta were associated^ as before 

 remarked^ with shells of existing species. These have not 

 as yet been examined with scrupulous care^ but it may be 

 safely asserted^ that they are most closely similar to the 

 species now living in the same bay : it is also very remark- 

 able^ that not only the species^ but the proportional num- 

 bers of each kind^ are nearly the same with those now cast 

 up on the pebble beaches. There are eleven marine species 

 (some in an imperfect state)^ and one terrestrial. If I had 

 not collected living specimens from the same bay, some of 

 the fossils would have been thought extinct ; for Mr. 

 Sowerby, who was kind enough to look at my collection, 

 had not previously seen them. We may feel certain that 

 the bones have not been washed out of an older formation, 

 and embedded in a more recent one, because the remains of 

 one of the Edentata were lying in their proper relative 

 position (and partly so in a second case) ; which could not 

 have happened, without the carcass had been washed to the 

 spot where the skeleton is now entombed. 



We here have a strong confirmation of the remarkable 

 law so often insisted on by Mr. Lyell, namely, that the 

 " longevity of the species in the mammalia, is upon the 

 whole inferior to that of the testacea.^^* When we proceed 

 to the southern part of Patagonia, I shall have occasion to 

 describe the case of an extinct camel, from which the same 

 result may be deduced. 



From the shells being littoral species (including one 

 terrestrial), and from the character of the deposit, we may 

 feel absolutely certain that the remains were embedded in a 

 shallow sea, not far from the coast. From the position of 

 the skeleton being undisturbed, and likewise from the fact 

 that full-grown serpulee were attached to some of the bones^ 



* Principles of Geology, vol. iv., p. 40. 

 VOL. III. II 



