THE AGE OF REPTILES 



frequently been obtained. They and two similarly 

 embedded and flattened skeletons of different kinds of 

 Ichthyosaurs may be seen in quantity on the wall of the 

 gallery of fossil reptiles in the Natural History Museum 

 at South Kensington. 



The Ichthyosaurs were much more fish-like or whale- 

 like in form than the Plesiosaurs. " They were, indeed, 11 

 says Sir E. Ray Lankester, " singularly like the porpoises 

 and grampuses among living whales and stand in the 

 same relation to land-living reptiles that the porpoises 

 do to land-living mammals. Their fish-like appearance and 

 fins are not primitive characters and do not indicate any 

 closer blood relationship to fishes than that possessed by 

 other reptiles. They are the offspring of four-legged terres- 

 trial reptiles which have become specially modified and 

 adapted to submarine life." Like many whales, they had 

 a fin on the back devoid of bony support. The Ichthyo- 

 saur had a ring of bony plates supporting the eyeball 

 (as birds also have), and these are often preserved in the 

 fossil specimens. 



At the end of the Triassic period some strata were laid 

 down which have been called "Beds of passage." We 

 have seen that the Triassic strata were probably deposited, 

 altogether or in part, in extensive salt lakes or inland 

 seas. At the close of the Triassic period the waters of 

 the ocean were admitted to these areas by the sinking of 

 the land at some point or other of their margins. With 

 the sea-water came many living things fishes, shells, 

 etc. and the very scanty life of the Triassic lake was 

 replaced by an abundance of marine life. These beds were 



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