entirely rejects Quenstedt's opinions with regard to their upright position. He makes the following remarks: 'The animal walked on the free fore-toes and bore the wings like a bat, though with the body not in an upright position like a bird, but four-footed. The hind-foot is much too small for such an upright position, and the fore-foot much too strongly developed. I therefore believe that the Pterodactyle could much better have walked four-footed than a bat, because it possessed so much better developed fore-feet.' In the length of the tibia Burmeister sees no reason for the upright position, but, as he says, only a means for the wide expansion of the flying-membrane;--and an endeavour in walking on four feet to bring the leg into the necessary harmony with the arm, which is so much elongated with the flat-hand. Hermann von Meyer[L]. [Footnote L: _Fauna der Vorwelt. Reptilien aus dem Lithographischen schiefer._ Frankfurt am Main. 1859. pp. 15-23.] The skull of the Pterodactyle can only be compared with those of birds and lizards. The form is essentially Avian, and the sutures are indistinct or obliterated as in birds, while in reptiles they are persistent The temporal bone enters into the formation of the reservoir for the brain, which is eminently characteristic of birds and quite different from anything found in lizards. The snout resembles a bird in being chiefly formed by the intermaxillary bone, which bounds the front of the anterior nares; and, as in birds, the bone extends backward between the eye-cavities to the frontal bone. The corresponding intermaxillary ridge of the Monitor is of less extent. The frontal-bone forms the highest part of the skull, and is similar to that of birds. The principal frontal is double, and forms the upper and hind part of the cavity for the eye, and covered the greater part of the large brain, composed of two hemispheres, in which Oken long ago saw a similarity to the higher animals. The arched form of the back part of the skull is bird-like. The double parietal adjoins the principal frontal, and is conditioned like the parietal in birds. The supra-occipital is single as in birds, expanded, and forms the part of the skull which extends furthest back. From the form of the back part of the skull it may be concluded that the foramen magnum was situated as in birds, and that the head and neck were moved as in birds, and not as in reptiles and mammals.