DTSTRIBUTIOIT OB OPHIDIAN'S. 
243 
deed, to favour the opinion that those animals were not 
numerous in antediluvian epochs, and that they did not 
exist at that remote period when the earth was inhabited 
by those Saurians of enormous magnitude, those singular 
animals known by the names of Plesiosaurus and Ichthy- 
osaurus, reptiles of which such fine remains are discovered 
in the Juracic and chalk formations. 
