74 



inclined to think that three thousand years is a moderate estimate for the 

 time required to form these mounds of refuse. 



The constitution of the Mammalian layer is, as would naturally be 

 expected, much more Iieterogeneous than that of either stratum previously 

 deposited. 



The contents, besides the remains of shells, fish, and occasionally of 

 echini, which have been previously enumerated, are principally as follows : 



LOWER MAMMALIAN LAYEK. 



Bones of the following mammals : 



Callirhimis ursimis, fur-seal. 



Eiimetopias Stelleri, sea-lion. 



Phoca, or hair-seals, two species. 



Bosmarus ohesus, walrus ; rarely in the eastern islands. 



Phoccsna vomerina, puffing-pig. 



Orca ater, the killer whale. 



MIDDLE MAMMALIAN LAYER. 



The above, and the following mammals and birds : 



Megaptera versahilis, the hump-backed whale. 



Diomedea hrachyura, the mottled albatross. 



Mormon corniailatus, the horned puffin. 



Mormon cirrhatus, the tufted puffin. 



Uria sp., several of the divers. 



Phaleris sp., several of the smaller aides. 



Lagopus alius, the ptarmigan. 



Larus leiicopteriis or glaucescens, the larger gulls. 



Eissa tridadyla, the kittiwake. 



And bones of several species of eiders and other ducks. 



UPPER MAMMALIAN LAYEK. 



All the preceding, and also the bones of — 

 Balmia Sieboldii, Pacific right whale. 

 Baloiua nigstkctus, bowhead or Polar whale. 



