MAMMALIA. 6 



cemented together by carbonate of lime, they are termed Pier-case 2. 



" bone-breccias " (Italian breccia, a crumb). Examples are 



shown from Gibraltar, from ]\linas Geraes, Brazil, and from 



the Vrelliugton Caves, New South Wales (Pier-case 2, top 



shelf). Treacherous ground, like a swamp or peat-bog, is 



often rich in the skeletons and other remains of animals 



which have become mired by accident. The salt marshes 



or " licks " of North America thus yield remarkable skeletons 



of the mastodon (Stand B), while the tundras of Siberia 



entomb innumerable carcases of the mammoth and woolly 



rhinoceros. 



Caverns. 



The ])one-bearing deposits on the floors of caverns in "Wall-case 

 limestone districts are particularly interesting, because in p. ■*•• „ 

 many cases the fossil remains have not been introduced by Table-case 

 accident, but by men or wild beasts which have inhabited 1- 



these retreats. In England and Wales, for example, a large 

 proportion of the caverns were hytena-dens during the 

 rieistocene period, and the remains both of the hyreuas and 

 of their prey are found in the red clay covering the floor. 

 Other caverns were inhabited by primitive man, either 

 exclusively by him or only at times when the hysenas were 

 driven out ; and in such cases there are articles of human 

 ^\'orkmansllip, traces of fire, and even l)oues of man himself, 

 in the same kind of deposit. This " cave-earth," as it is 

 termed, is mainly the residue of decomposed limestone, and 

 it is mixed with drippings of lime-water, which evaporate 

 and leave a crust of carbonate of lime, When a cavern 

 l)ecomes deserted and the drippings are undisturbed, the 

 limy crust thickens slowly into a layer of " stalagmite," 

 \\hich seals up whatever may be l^eneath in a permanent 

 state of preservation. A specimen of the resulting floor 

 from Brixham Cave, near Torquay, enclosing an antler of a 

 reindeer, is seen in Wall-case 1. An interesting piece of 

 stalagmite enclosing human remains, from the cavern of 

 Bruniquel, France, is also sliown in the same case. 



Mammals of Pleistocene Europe. 



Unfortunately, the surface (jf the land changes so rapidly 

 by weathering and "denudation" (natural wearing down 

 and washing away), that no once-inhabited caverns hitherto 

 discovered date liack further than tlie I'lcistocene period. 



B 2 



