310 



PALAEONTOLOGY. 



Pliascolotlierium has four true, and three false, molars. 

 Of this genus only one species is known. Two extinct 

 species of Didelphis, all the living species of which aro 

 limited to America, are found in the eocene of Montmartre, 

 at Kyson in Suffolk, and in the caverns of Brazil. Species of 

 Dasyurus, Thylacinus, JIalmaturus, Hypsiprifaus, are found 

 in the caverns of New Holland. 



MAMMALIA MONADELPHIA. 



The organs of locomotion, of touch, and of mastication 

 afford characters for the sub-division of the monodelphians 

 into the following orders : 



1st Order. CETACEA. Eesemble fishes in their external 

 contour; the anterior extremities are shortened and en- 



FIG. 217. Balsena mysticitos. 



veloped in skin to form fins, but in the frame-work of these 

 organs we find the representative bones of the arm and hand 



