Ch. XII.] MASTODON GIGANTEUS. 143 



absence of testacea in the deep sea, where the undisturbed accumulation 

 of boulders melted out of coast-ice and icebergs may take place. In the 

 uE^ean and other parts of the Mediterranean, the zero of animal life, 

 according- to Prof. E. Forbes, is approached at a depth of about 300 

 fathoms. In tropical seas it would descend farther down, just as vegeta- 

 tion ascends higher on the mountains of hot countries. Near the pole, 

 on the other hand, the same zero would be reached much sooner both 

 on the hills and in the sea. If the ocean was filled with floating bergs, 

 and a low temperature prevailed in the northern hemisphere during the 

 glacial period, even the shallow part of the sea might have been unin- 

 habitable, or very thinly peopled with living beings. It may also be 

 remarked that the melting of ice in some fiords in Norway freshens the 

 water so as to destroy marine life, and famines have been caused in Ice- 

 land by the stranding of icebergs drifted from the Greenland coast, 

 which have required several years to melt, and have not only injured the 

 hay harvest by cooling the atmosphere, but have driven away the fish 

 from the shore by chilling and freshening the sea. 



If the cold of the glacial epoch came on slowly, if it was long before 

 it reached its greatest intensity, and again if it abated gradually, we may 

 expect to find the earliest and latest formed drift less barren of organic 

 remains than that deposited during the coldest period. We may also 

 expect that along the southern limits of the drift during the whole gla- 

 cial epoch, there would be an intimate association of transported matter 

 of northern origin with fossil-bearing sediment, whether marine or fresh- 

 water, belonging to more southern seas, rivers, and continents. 



That in the United States, the Mastodon giganteus was very abundant 

 after the drift period is evident from the fact that entire skeletons of this 

 animal are met with in bogs and lacustrine deposits occupying hollows 

 in the drift. They sometimes occur in the bottom even of small ponds 

 recently drained by the agriculturist for the sake of the shell marl. I ex- 

 amined one of these spots at Geneseo in the state of New York, from 

 which the bones, skull, and tusk of a Mastodon had been procured in 

 the marl below a layer of black peaty earth, and ascertained that all the 

 associated freshwater and land shells were of a species now common in 

 the same district. They consisted of several species of Lymnea, of Pla- 

 norbis bicarinatus, Physa heterostropha, &c. 



In 1845 no less than six skeletons of the same species of Mastodon 

 were found in Warren county, New Jersey, 6 feet below the surface, by 

 a farmer who was digging out the rich mud from a small pond which 

 he had drained. Five of these skeletons were lying together, and a large 

 part of the bones crumbled to pieces as soon as they were exposed to the 

 air. But nearly the whole of the other skeleton, which lay about 10 

 feet apart from the rest, was preserved entire, and proved the correctness 

 of Cuvier's conjecture respecting this extinct animal, namely, that it 

 had twenty ribs like the living elephant. From the clay in the interior 

 within the ribs, just where the contents of the stomach might naturally 

 have been looked for, seven bushels of vegetable matter were extracted. 



