Reviews — Prof. H. G. Seeley on Ornithosauria. 125 
essentially avian in character, and are not “ adaptive modifications,” 
to any reptilian form “ consequent upon the parts of the body having 
had to perform identical functions — seeing that the Cheiroptera 
among mammals have great powers of flight without the skeleton 
being pneumatic.” Upon this character he also further remarks : “The 
pneumatic foramina of Ornithosaurs so closely resemble those of 
birds in almost every bone of the skeleton, that the resemblance 
often amounts to complete coincidence. The holes are usually in 
exactly the same positions on each of the bones in both groups ; and 
in both they have the same details of reticulate structure. It must 
then be sound physiology to infer that such identity of structure is 
due to identical causation.” These well-ascertained facts, in the 
author’s opinion, tend to prove that the respiratory and circulatory 
organs wei - e near akin to those of the bird, and, as a consequence, 
the Ornithosaurs were hot-blooded, and therefore not reptilian. Prof. 
Huxley, commenting elsewhere upon the high development of these 
organs in the Pterodactyles, thinks it highly probable that they had 
hot blood, but nevertheless that they were reptiles, with special 
modifications for special purposes. These conclusions Prof. Seeley 
contends cannot be accepted. 
We may here remark that Prof. Owen, in his latest memoir upon 
these animals, as positively maintains that their affinities are reptilian 
rather than avian, and that by the absence of feathers as a heat-con- 
serving covering they were also cold-blooded. It is a remarkable 
fact that no trace of scales, hair, or feathers, or of iutegumentary 
covering, have ever been found associated with their osteological 
remains in deposits, like the Solenhofen Limestone, so peculiarly 
adapted for their preservation. 
The other vital character that Prof. Seeley advances in support of 
his argument is the stucture of the brain ; the evidence for which 
“rests upon the form of the cerebral hemisphere in Pterodactylus 
longirostris and other specimens from the lithographic slate,” on a 
specimen from the Wealden, and on some fragments showing por- 
tions of the brain-cavity from the Cambridge Upper Greensand ; 
these he compares with the brain-cavity in the skull of an Owl, and 
fully describes, with minute anatomical detail, the many points in 
which the structural characters are common to both, and as the 
result of these comparisons he observes, that “ the resemblance of 
form and arrangement of parts between this fossil animal’s brain 
and the brain of a bird amounts, as far as the evidence goes, to 
absolute identity — the cerebrum being the cerebrum of a bird, the 
optic lobes those of a bird, and the cerebellum that of a bird, no 
more perfect specimen could add to the force of the conclusion that 
the Ornithosaurian brain is an avian brain of typical structure.” 
On these resemblances in vital structure chiefly rests the claim of 
the Ornithosauria to be classified with the birds, which if allowed, 
they are only separated from the carinate and other birds by such 
modifications of the skeleton, as distinguish Cetacea, Carnivora, and 
Monotremata among Mammals from each other. 
The recent discovery in America of undoubted ornithic remains, 
