102 CLARIFICATION OP AMPHIBIANS. 



more characteristic of a former world than of this : the 

 existing species, comparatively, are few, and exhibit but 

 little variation in structure. We are therefore justified 

 in supposing that those intermediate gradations of form^ 

 between a turtle and a cuttle-fish, are either extermin- 

 ated, or remain still hid in the unfathomable depths of 

 ocean. The connection of the reptiles to the succeeding 

 class of birds is also interrupted, but by no m.eans 

 indeterminate. It has been stated, indeed, that the 

 tortoises, while they lead on one hand to the Cepha- 

 lopoda, or cuttle-fish, conduct us at the same tim_e to 

 birds, in support of which several ingenious comparisons 

 have been drawn between a turtle and a penguin {^Hor. 

 Ent. 264.). But it must be remembered that this bird 

 does not, '' like a turtle, drag itself on its belly," but 

 walks perfectly erect; and, in the second place, that if the 

 tortoises really make the nearest approach to the Cephalo- 

 poda, then the transition to birds must be effected by some 

 other group. Nov,^ this other group, which, according to 

 the theory of representation, would make the nearest ap- 

 proach to birds, is composed of the Enalosaures, or fish- 

 lizards, which have fins similar to the tortoises, and very 

 analogous to the penguins : the mouth also is prolonged 

 into a rostrum, or lengthened bill. This latter character 

 is still more conspicuous in those most extraordinary fossil 

 animals, the Pterodactyli, or flying lizards, where we see, 

 for the first time among reptiles, the fore feet converted 

 into wings. To attempt to demonstrate the natural sta- 

 tion of these flying reptiles, now only known by their 

 fossil bones, might be thought too speculative; but 

 their whole structure assimilates them more to the Enalo- 

 saures than to any other division of reptiles : and in 

 comprehending them as aberrant forms of that group, we 

 preserve its chief characteristic of being an extinct 

 order, and do no violence to nature in supposing that 

 she would connect the reptiles to birds by some tribe of 

 the former animals which had the power of flight. 



(107.) The relation of reptiles to fish on one side, 

 and to the true Amphibia upon the other, is so apparent. 



