TEDIGREE OF BIRDS. 265 



or lizard-like animals. The scale of a lizard and a 

 feather seem to be totally different things ; but in their 

 rirst rudiments they are completely identical, and the 

 feather has a far greater analogy with the scale, than with 

 the hair. The plumage, which seems to impress a spe- 

 cific character upon the bird, is therefore to be traced 

 from the formation of scales. Of the internal soft organs, 

 we will only remark upon the heart and lungs. All the 

 older geologists placed the heart of the bird on the same 

 level with that of the mammal and of man ; in its specific 

 arrangements, however, it is only to be interpreted by 

 the heart of the reptile, and the wind-pipe is not ramified 

 as in the mammal. That the reptiles exhibit a gradual 

 transition to the leg of the bird, has been repeatedly 

 pointed out. The pelvis of the bird, which is remarkable 

 for the length of the pubis and ischium, and is open in 

 front, likewise represents only a slight advance in develop- 

 ment upon the pelvic structure already shown in several 

 of the Ornithoscelidae. Thus Huxley says with reference 

 to the ischium of the Hypsilophodae, that *' the remark- 

 able slenderness and prolongation of the ischium give it 

 a wonderfully ornithic character." Finally, in the skull, 

 'peculiarities possessed by the bird in contrast with the 

 mammal, such as the simple condyle of the occiput, the 

 quadrate bone, the cochlea of the auditory labyrinth, the 

 composition of the lower jaw, its articulation with the 

 skull by the intervention of the quadrate bone, &c., are 

 not specific characters of the bird alone, but of reptiles in 

 general. This similarity of type in reptiles and in birds 

 !s perfectly manifest from the comparison of living birds 

 with living reptiles. But the proof that the bird is 

 derived from the reptile is rendered unimpeachable by 



