2348 THE TIN AM US, FLIGHTLESS BIRDS, ETC. 



as of equal importance with the two together. In size these birds were about equal 

 to rooks, with which they agree in being evidently adapted for perching on the 

 boughs of trees. In addition to the possession of a small number of conical teeth 

 in the short jaws, they are characterized by having a long, lizard-like, tapering tail 

 (which gives the name to the group), and from each joint of this a pair of feathers 

 take origin. In this respect they differ from all the birds hitherto noticed, in the 

 whole of which the bones of the tail are shortened, the tail feathers arising in a fan- 

 shaped manner from its terminal joint. In addition to this, they are further charac- 

 terized by the first three metacarpal bones of the wing, as well as those representing 

 the corresponding fingers, being perfectly distinct from one another, and each termi- 

 nal joint of the latter being furnished with a well-developed claw; all other birds 

 having the metacarpal bones, as well as some of those of the fingers, welded to- 

 gether; while there are, at most, but two claws (in the young of the seriema). It 

 may be mentioned here that although the three-clawed digits in the wing of the 

 lizard-tailed birds are commonly regarded as representing the first, second, and third 

 of the typical five-fingered limb, Mr. C. H. Hurst believes that they really repre- 

 sent the second, third, and fourth; and he is thus led to conclude that the same will 

 hold good for the digits in the wing of an ordinary bird. Be this as it may, in hav- 

 ing cup-shaped articular surfaces to the bodies of the vertebrae, the lizard-tailed 

 bird resembles the later Ichthyornis; but it differs from all other members of the class 

 in having the three bones constituting the pelvis perfectly distinct from one another 

 (as in most reptiles), while in the leg the tibia and fibula are likewise separate. As 

 regards the general structure of the wing and leg, these remarkable birds agree, 

 however, with their modern allies, the foot having a complete canon bone, and but 

 four toes, of which the first is directed backward. In the absence of hook-like 

 (uncinate) processes to the ribs, Arch&opteryx would appear to be more specialized 

 than ordinary birds, seeing that these elements exist in many reptiles; while in the 

 possession of a perfectly formed canon bone, it would appear to be on a higher 

 level than the penguins. 



Finally, it will not fail to be noticed that although some of these toothed birds 

 exhibit certain specialized features suggesting that they are not the direct ancestors 

 of modern birds, yet that, on the whole, they afford a most valuable contribution in 

 favor of the doctrine of evolution, approximating more and more, as we descend in 

 the geological scale, to reptiles, from which it may be confidently stated the Avian 

 class has originated. 



