BIRD OR REPTILE WHICH ? 73 i 



their contemporary the archseopteryx did ; for the constant correlative 

 structure with hot-bloodedness is a non-conducting covering for the 

 body. Prof. Huxley, on the other hand, differing from this anatomist, 

 thinks that, judging from the air-passages in their bones, they were 

 warm-blooded, but that, nevertheless, they were reptiles with special 

 modifications for special purposes. 



It would, therefore, appear that we are again face to face with a 

 group which the most eminent authorities are far from agreed whether 

 to regard as reptiles or as birds. 



We have now passed in review various remarkable forms living 

 birds and living reptiles, separated by an immeasurable distance from 

 each other, and forms which have so mingled the characters of both as 

 to present great difficulties to their being included among the members 

 of either group. Starting from the groveling crocodile, we have seen 

 that there existed gigantic crocodile-like forms, such as the giant-lizard 

 and the iguanodon, that walked, sometimes at least, oil their hind- 

 limbs ; others, like the long-necked, long-tailed compsognathus from 

 the Solenhofen slates, that hopped on the ground after the manner of 

 a bird ; then " flying dragons," with birdlike brain and bones that 

 cleft the air with their twenty-feet expanse of wing ; next, undoubted 

 birds, with toothed bills, the one with reptilian vertebra?, the other with 

 a beaver-like tail ; while last of all, omitting the imperfectly known 

 Sheppey fossil, the feathered archasopteryx whose twenty caudal seg- 

 ments bar its entrance to every existing family of birds. 



Without by any means asserting what is not only far from being 

 ascertained fact, but is indeed very improbable ; for we are not in a 

 position to state that they appeared on the earth intennediately be- 

 tween the two groups that these forms are the direct terms in the 

 series of progressions from reptiles to birds, we can, in their intelligent 

 contemplation, without overstraining the imagination or violating our 

 reason, picture still more modified forms wherein the reptilian and the 

 avian types would so harmoniously blend that we should find it im- 

 possible to say, " At this point the line between reptiles and birds must 

 be drawn." There can be no reasonable doubt but that the remains, 

 which only through the circumstance of a happy burial have been pre- 

 served to us from the second great era of the world's history till now, 

 are no more than a very few examples with many a blank between of 

 the fauna which has lived and died, whose tombs no man knoweth. 

 Moreover, it seems easy enough to believe, after studying these forms, 

 that, could any human eye have followed from that day to this the wax- 

 ing and waning of the various animal groups, he could have constructed 

 for us a marvelous chain of existences between reptiles and birds, the 

 conformation of whose unknown links we can almost fabricate in our 

 minds, between which no abrupt transitions harshly jarring would oc- 

 cur, no stepping-stones too wide to stride across ; and, handing on to 

 us, besides, the traditions of a still earlier time, he could have pictured 



