The stump was attached to the side of the outer toe. Wagner, in P. Kochi, supposed it to be on the inner side, and so gave a reverse arrangement to the toes. The stump may be compared with that of some Chelonians, in which it is not furnished with a claw. There is a difference from birds in the claws being much less developed. It has a true reptile foot. In bats the toes are of equal length. Von Meyer thinks the hind-legs did not enable it to walk on the land. In some Pterodactyles the flying-membrane is faintly seen. The presence of feathers might be inferred from there being but one finger for flighty as in birds; but the function of feathers is subserved by the long and stiff finger. If it had been covered with scales, as was supposed by Cuvier, some traces of them would be found. The skin was probably naked, and had no connection with the hind-legs as it has in bats; in this respect resembling birds. The condition of the several parts of the skeleton completely proves that the Pterodactyle was a reptile. Its head, neck, shoulder, and back, resemble a bird; while there are, on the other hand, some striking resemblances with the reptile in the pelvis, tail, and articular parts of the limbs. Sometimes the characters of the two classes run side by side, as in the skull, the fore-limbs, and especially in the hind-limbs, where the shin of a Bird is connected with the foot of a Saurian. The parts in which it corresponds with birds show that Pterodactyles also were flying animals. That we should be entitled to conclude, from the hollow state of the bones, that they belonged to flying animals, is sufficiently proved by Blumenbach, Buckland, Mantell, Owen having mistaken them for bones of birds. The most absolute proof that it was a flying animal is the pneumatic character of its bones. This condition was discerned by me in some Pterodactyle bones from the Lias of Franken (_Jahrb. für Mineral_, 1837, p. 316), and was afterwards established by Owen in the Pterodactyles from the Chalk of England. This structure was previously only known in birds. And the supposition readily follows that in the respiratory process there was some similarity between the Pterodactyle and the Birds. They have the proportions of upper-arm and fore-arm which characterize birds of great flight, the humerus short and the fore-arm long; hence it may be presumed that Pterodactyles could fly well. From the absence and presence of the bony sclerotic ring in the eye, it may be supposed that the Pterodactyles were active in the day-time, while Rhamphorhynchus was nocturnal.