236 THE HISTORY OF CREATION. 



orders of Beaked animals represent but a single degenerated 

 branch developed on one side — probably possessed a very 

 highly developed jaw like the marsupial animals, which 

 developed from them. 



Marsupial, or Pouched Animals (Didelphia, or Marsu^ 

 pialia), the second of the three sub-classes of Mammals, 

 form in every respect — both as regards their anatomy and 

 embryology, as well as their genealogy and history — the 

 transition between the other sub-classes — the Cloacal and 

 Placental Animals. Numerous representatives of this group 

 stiU exist, especially the weU-known kangaroos, pouched 

 rats, and pouched dogs; but on the whole this sub-class, 

 like the preceding one, is evidently approaching its complete 

 extinction, and the living members of the class are the last 

 surviving remnants of a large group rich in forms, which 

 represented the Mammalia during the more recent secondary 

 and the earlier tertiary periods. The Marsupial Aiimals 

 probably developed towards the middle of the Mesolithie 

 epoch (during the Jura) out of a branch of the Cloacal 

 Animals, and in the beginning of the Tertiary epoch again, 

 the group of Placental Animals arose out of the Marsupials, 

 and the latter then succumbed to the former in the struggle 

 for life. All the fossil remains of Mammals known to us from 

 the Secondary epoch, belong either exclusively to Marsupials, 

 or partly perhaps to Cloacal animals. At that time Marsu- 

 pials seem to have been distributed over the whole earth ; 

 even in Europe (France and England), well-preserved fossil 

 remains of them have been found. On the other hand, the 

 last off-shoots of the sub-class now living are confined to a 

 very narrow tract of distribution, namely, to Australia, the 

 Australasian, and a small part of the Asiatic, Ai-ehipelago. 



