of opinion that these flying dragons "had a brain indistinguishable from a bird's."
They are all remarkable for their great proportionate length of head and neck, for in some the lizard-like and in others the birdlike length of tail, and for the large size of the fore-limb, which, quite unlike the same extremity in a bird, was terminated by four digits, whereof three were clawed, while the clawless fourth or little finger was enormously elongated to support the outer edge of an expansion of the integument like the wing of a bat. The bones of the hind-limb and of the haunch differ widely from the bird type; nevertheless, air-passages, such as characterize no other kind of skeleton, are met with in the bones of the head, of the spine, and of the fore and hind limbs, often coinciding identically in situation with those in birds, and indicate, according to Prof. Seeley, a system of air-circulation from the lungs similar to what is found in birds. From this he argues the existence in these gigantic volants of warm blood, and of a heart similar to the bird's in construction. They have the breastbone broad, strongly keeled, and unlike that of other reptiles; there is evidence also that the jaws were incased in a horny sheath. On these considerations, therefore, it is held that, as far as the skeleton indicates, their differences from birds are much less than the differences between the several orders of mammals or reptiles. The same paleontologist has made careful casts of the interior of the skull, and, from the position of certain lobes whose distance or proximity distinguishes the brains of modern birds and reptiles, he says in an interesting paper on the subject in the Linnæan Society's "Transactions" for 1876: "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; no more perfect specimen could add to the force of the conclusion that its brain is an avian brain of a typical structure. Since brain and lungs are organs of incomparably greater value in questions of organization than fore and hind limbs—organs in which, according to Prof. Huxley, they depart most widely from the bird type—the flying dragons on the whole are very reptilian birds rather than very avian reptiles."
The Solenhofen stone preserves not only bones and hard parts, but even the cutaneous characters of its old inhabitants. It shows casts of the down and feathers, impressions of the fine foldings or wrinkles of thin expansions of naked skin, as well as of delicate tendons. Prof. Owen, therefore, thinks that if the flying dragons had possessed any plumose clothing it would in all probability have been preserved, and, as no such indications (but contrariwise, several genera undoubtedly had their body-covering hardened into bony scales, sometimes produced into prodigious spines) have been discovered, though the Oolitic mud has entombed the greatest number and variety of these beings, he concludes that they were cold-blooded, as other reptiles are; whereas, if they had been warm-blooded, they would have possessed feathers, as
