Archeopteryx macrura. 453 
Nor can I familiarize myself more with the view of Prof. 
Huxley, who sees the ancestors of Birds in the Dinosaurs 
taken as a whole. I have already remarked that the elonga- 
tion of the anterior extremities is an indispensable condition 
of the faculty of flight, and that the Dinosaurs, on the con- 
trary, show the same shortening of these fore-limbs that we 
observe in animals that leap. 
It is true that the Dinosaurs exhibit in the structure of 
their pelvis, their tarsi, and their digits many approxima- 
tions to Birds. It is also true that the embryo of Birds shows 
that the single metatarsal comes from the fusion of the tarsals 
and metatarsals. which are originally separate, as in Reptiles. 
We therefore acknowledge here a genetic line, proved by 
both phylogeny and ontogeny ; and we do not hesitate to say 
that the legs of the Dinosaurs form the bond of union be- 
tween that of Reptiles, strictly so called, and that of Birds. 
But there our genetic line stops, and if we consider the fore- 
feet we see no approximation. A mere stump renders flight 
impossible. In my opinion, a genetic line starting from the 
Dinosaurs could only reach the Ratites. Now we have many 
indications that this isa very ancient group. A host of points 
in their anatomy approximates them, more than any other 
known group of living Birds, to the Reptiles. The Hesper- 
ornis, of the American Cretaceous deposits, is, according 
to Prof. Marsh, an aquatic Ostrich, having the keelless 
sternum and the rudimentary wings of a Ratite. This view, 
the reasons of which I have just poimted out im a very sum- 
mary way, without being able to explain them, would com- 
pel consequences opposed to the opinions now received. If 
we adopt it we must see in the wing of the Ratites, not a 
Bird’s wing become rudimentary through disuse, but, on the 
contrary, an organ which, owing to its origin, has not yet 
been able to become a perfect wing. We must also see in 
it the fore foot of a Dinosaur, developed with a view to the 
organization of a Bird, but tainted with the original fault of 
being too short and too small, so as to hinder it from becom- 
ing an organ of active flight. The Ratites, far from being a 
degenerate group proceeding from Birds that fly, would be, 
