MAMMALIA. 3 



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



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



shown from Gibraltar, from Minas Geraes, Brazil, and from 



the Wellington 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 bone-bearing deposits on the floors of caverns in Wall-ease 

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

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

 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 hysena-dens during the 

 Pleistocene period, and the remains both of the hysenas 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 

 workmanship, traces of fire, and even bones 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 

 becomes deserted and the drippings are undisturbed, the 

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

 which seals up whatever may be beneath 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-ease 1. An interesting piece of 

 stalagmite enclosing human remains, from the cavern of 

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



Mammals of Pleistocene Europe. 



Unfortunately, the surface of the land changes so rapidly 

 by weathering and " denudation " (natural wearing down 

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

 discovered date back further than the Pleistocene period. 



B 2 



