244 THE STOKY OF THE EARTH AND MAN. 



bered shells of Foraminifeva. These may serve as 

 illustrations of the functions of these humble inhabi- 

 tants of the sea as accumulators of calcareous matter. 

 It is further interesting to remark that some of the 

 beds of nummulitic limestone are so completely filled 

 with these shells, that we might from detached speci- 

 mens suppose that they belonged to sea-bottoms 

 whereon no other form of life was present. Yet some 

 beds of this age are remarkably rich in other fossils. 

 Lyell states that as many as six hundred species of 

 shells have been found in the principal limestone of 

 the Paris basin alone; and the lower Eocene beds 

 afford remains of fishes, of reptiles, of birds, and of 

 mammals. Among the latter are the bones of gigan- 

 tic whales, of which one of the most remarkable is the 

 Zeuglodon of Alabama, a creature sometimes seventy 

 Ceet in length, and which replaces in the Tertiai-y the 

 great Elasmosaurs and Ichthyosaurs of the Mesozoic, 

 marking the advent, even in the sea, of the age of 

 Mammals as distinguished from the age of Eeptiles. 



This fact leads us naturally to consider in the second 

 place the mammalia, and other land animals of the 

 Tertiary. At the beginning of the period we meet 

 with that higher group of mammals, not pouched, 

 which now prevails. Among the oldest of these 

 Tertiary beasts are Coryphodon, an animal related to 

 the Modern Tapirs, and Arctocyon, a creature related 

 to the bears and racoons. These animals represent 

 respectively the Pachyderms, or thick-skinned mam- 

 mals,, ar.d the ordinary Carnivora. Contemporary with 



