OF ORGANIC NATURE. 49 



eight orders, or thereabouts, which you can make among 

 reptiles, one-half are extinct. These diagrams of the 

 plesiosaurus, the ichthyosaurus, the pterodactyle, give 

 you a notion of some of these extinct reptiles. And here 

 is a cast of the pterodactyle and bones of the ichthyo- 

 saurus and the plesiosaurus, just as fresh as if it had 

 been recently dug up in a churchyard. Thus, in the 

 reptile class, there are no less than half of the orders 

 which are absolutely extinct. If we turn to the 

 Amphibia, there was one extinct order, the Labv- 

 rinthodouts, typified by the large salamander-like beast 

 shown in this diagram. 



. No order of fishes is known to be extinct. Every 

 fish that we find in the strata — to which I have been 

 referring — can be identified and placed in one of the 

 orders which exist at the present day. There is not 

 known to be a single ordinal form of insect extinct. 

 There are only two orders extinct among the Crustacea. 

 There is not known to be an extinct order of these 

 creatures, the parasitic and other worms; but there 

 are two, not to say three, absolutely extinct orders of 

 this class, the Echinodermata ; out of all the orders of 

 the Cceknterata and Protozoa only one, the Rugose 

 Corals. 



So that, you see, out of somewhere about 120 orders 

 of animals, taking them altogether, you will not, at 

 the outside estimate, find above ten or a dozen extinct. 

 Summing up all the order of animals which have left 

 remains behind them, you will not find above ten or 

 a dozen which cannot be arranged with those of the 

 present day ; that is to say, that the difference does 

 not amount to much more than ten per cent. : and the 



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