FOSSIL VERTEBRATES—AVES 817 
warrant our acceptance of either of these forms. Haeckel in his 
work on the phylogeny of the vertebrates thinks that the 
ancestor of the birds must be sought among the most primitive 
of the Dinosaurs of the Triassic or even earlier, among the 
Rhyncocephalia and the Proganosauria. Smith Woodward in his 
very recent work on Vertebrate Paleontology is content to say, 
“The earliest known birds exhibit a distinct approach to the 
Reptitia in several characters, but do not afford any indication as 
to the particular group from which they evolved. The general 
opinion is, that they are more closely related to certain Dino- 
sauria than to any other forms hitherto discovered.” 
Following the classification adopted by Smith Woodward and 
in Parker and Haswell’s Zodlogy, the class Aves may be 
divided into two subclasses, Avch@ornithes and Neornithes,; the 
same groups were called by Haeckel, Saururae and Ornithurae. 
The first subclass is characterized by the features mentioned 
above. There is but one genus known and this is represented 
by but three specimens, two nearly perfect skeletons and a 
single impression of a feather. 
Archeopteryx from the Lithographic Beds of the Upper 
Jurassic of Bavaria. Besides the characters mentioned above 
the animal was distinguished by the possession of a very long 
bony tail with a pair of feathers growing from each vertebra. 
The body of the animal was well covered with feathers and the 
remiges of the wings were well developed. It was about the 
size of the ordinary crow. 
The (eornithes are divided into two groups, the Ratte and 
the Carinate; the flightless and the flying birds. The first 
group is of rather variable limits, some authors including in it 
all the birds without wings or with poorly developed wings with- 
out a keel upon the sternum, and without considering the origin 
of the condition, whether it is original, persistent from very 
early forms, or whether it is the result of degeneration from 
lack of use. Thus Smith Woodward includes among the Ratite 
certain forms that are considered by other authors degenerate 
Carinate. 
