﻿Revieivs — Frof. H. Q. 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 Clieiroptera 

 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 were 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 

 oi'gans 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 rejDtilian 

 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 integumentary 

 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 ai-e 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, 



