Archeeopteryx macrura. 455 
But, thanks to the exceptional fineness of the paste of the 
lithographic stones, the feathers are found, attached to the 
manus and tail of a Reptile, and to the leg of a Bird. Who, 
then, could deny the existence of feathers, more or less deve- 
loped, or more or less rudimentary, in many of the ancient 
Reptiles, of which we have only found the skeletons or de- 
tached bones, embedded in a coarser matrix and one incap- 
able of preserving delicate imprints? I believe I have 
proved, from what goes before, that the adaptation for flight 
proceeds from without inwardly, from the skin to the skel- 
eton, and that the latter may be wholly unaffected when the 
former has already reached the development of feathers. 
Must we not admit that Archeopteryx, whose skeleton has 
undergone such slight modifications, contrasted with the 
luxuriant development of feathers, has been preceded by 
forms of terrestrial Reptiles whose skeleton had undergone 
no change, among which forms, instead of perfect feathers, 
there existed only the stumps of rudimentary feathers, such 
as at present are shown by the embryo of Birds in the egg? 
The cutaneous structures being destroyed by fossilization in 
the midst of a coarser matrix, what means would remain for 
us to recognize in a terrestrial Lizard witha normal skeleton 
the traces of a rudimentary plumage in the course of de- 
velopment ? 
To support these considerations I have no need here to 
recall to mind that the homology between the scales, warts, 
spines, and other cutaneous structures in Reptiles on the one 
hand, and the feathers of Birds on the other, has long since 
been recognized (see Gegenbaur’s ‘ Manual of Comparative 
Anatomy ’), and that all these Reptilian structures differ in 
nothing from the wart-like stumps which appear in the em- 
bryo of Birds as the first traces of plumage—that the Bird’s 
feather is only the Reptile’s scale further developed, and that 
the Reptile’s scale is only a feather that has kept the em- 
bryonic stage. There can thus be no doubt that the feathers 
of Archeopteryx, so fully developed as they are, must have 
been preceded, in other, older Reptiles, by cutaneous struc- 
tures representing the different degrees of embryonic develop- 
