OF ORGANIC NATURE. 49 



but have at present no representatives ? That is the 

 sense in which I meant to use the word " extinct." I 

 mean that those animals did live on this earth at one 

 time, but have left no one of their kind with us at the 

 present moment. So that estimating the number of 

 extinct animals is a sort of way of comparing the past 

 creation as a whole with the present as a whole. To 

 make that clear, I have written in red ink on these 

 diagrams the names of all those extinct orders, and in 

 black ink the names of the rest. Among the mammalia 

 and birds there are none extinct ; but when we come 

 to the reptiles there is a most wonderful thing : out of 

 the 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 the cast of the pterodactyle and bones of 

 the ichthyosaurus 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 Labyrintho- 

 donts, 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 crea- 

 tures, the parasitic and other worms ; but there are two, 

 not to say three, absolutely extinct orders of this class, 

 3 



