l8o THE CHAIN OF LIFE. 



question arises, was this resemblance merely that of two 

 oviparous bipeds, or anything more? and when we set off 

 against the resemblance in haunch bones and hind limbs, the 

 entire dissimilarity in head, in fore limbs, in vertebrae, in tail, 

 and probably in external covering, we are disposed to agree 

 with Huxley in his statement, with respect to the Struthious 

 birds, that their " total amount of approximation to the reptilian 

 type is but small ; and the gap between reptiles and birds is 

 but very slightly narrowed by their existence." There is 

 therefore here a great gap, even in the linking together of the 

 types, independently of any question of derivation. 



The second line of connection appears at first sight more 

 promising. Archseopteryx has a reptilian tail, and claws on 

 the wing ; and, if it had toothed jaws, like some of the birds in 

 the Cretaceous, must have altogether made a much nearer 

 approach to a reptile than any modern bird does. The re- 

 markable "fish-bird" (Ichthyornis) of Marsh is also very 

 reptilian in some of its characters. But when we compare 

 these reptilian birds with the Pterodactyls and their allies, a 

 vast gap at once becomes apparent. Disregarding the ex- 

 ternal clothing, we find the wing in the two groups entirely 

 dissimilar in details of construction, and this dissimilarity 

 extends to the hind limbs as well, so that the locomotive 

 organs resemble those of bats rather than those of birds. 



Without committing ourselves to any doctrine of develop- 

 ment, we might have rejoiced if our geological discoveries had 

 established a continuous chain, or two continuous chains, of 

 being between the reptiles and the birds ; but this end is evi- 

 dently still far from being attained, though some approximation 

 has undoubtedly been made. To quote again the admission 

 of Huxley : " Birds are no more modified reptiles than reptiles 

 are modified birds, the reptilian and ornithic types being both 

 in reality somewhat different superstructures, raised upon one 

 and the same ground-plan" — that ground-plan being the 

 idea of the air-breathing oviparous vertebrate, and the reptile 



