saurus, in the Kupferschiefer, and two others, Phanerosaurus and Sphenosaurus, different from them and from one another, in the Rothliegende, in which formation also a peculiar Labyrinthodont, Osteophorus, occurs.
Proterosaurus appears to me to be a true Lacertilian. At least, neither in Von Meyer's figures and descriptions, nor in the one classical specimen which exists in this country can I find evidence of any essential departure from the old Lacertilian plan of structure, such as is exhibited by Hyperodapedon or Telerpeton—though it must be confessed that the long neck, light head, and short fore- limbs, to say nothing of the opisthotonic death-spasm which has left the fossils in their present position, remind one curiously of Compsognathus.
Parasaurus has four ankylosed sacral vertebræ, with great sacral ribs; and perhaps the two vertebræ which succeed these must be counted as sacral. It would appear from the figures, that the anterior ribs may have been, and probably were, divided into a distinct capitulum and a tuberculum. Prom the position of the undisturbed femora in one specimen, it cannot be doubted that the ilia must have extended a long way in front of the acetabulum. The length of the short and stout femur does not exceed that of four conjoined vertebræ; and there is some reason to think that the bones of the leg were considerably longer than the femur.
Parasaurus therefore belongs to a totally different group of reptiles from Proterosaurus, and I can compare it with nothing but the Ornithoscelida and the Dicynodontia.
The structure of both Proterosaurus and Parasaurus leads to the belief that they were terrestrial reptiles; and their occurrence in the Kupferschiefer is no bar to this conclusion, as land-plants abound in that rock.
The Phanerosaurus of the Rothliegende is based upon a series of half-a-dozen vertebræ, the characters of which are altogether peculiar.
Sphenosaurus, on the other hand, seems to me to be a Lacertilian, though of a very different character from Proterosaurus.
On the whole, I am disposed to think that Parasaurus is related on the one hand to the Ornithoscelida and the Dicynodontia, and on the other to some much older and less specialized reptilian form. I can by no means bring myself to believe that the Reptilia commenced their existence in the Permian epoch with such specialized characters as are observable in the four known genera of that age.
4. The affinities of the Ornithoscelida with Birds.
I have treated of the relations of the Ornithoscelida with birds at length in a former paper, and I will merely repeat here that I know of no circumstance by which the structure of birds, as a class, differs from that of reptiles, which is not foreshadowed in the Ornithoscelida. Nor am I acquainted with any reptiles which can be compared in the strength and minuteness of their ornithic affinities with the Ornithoscelida.
It may be said that the form and mode of connexion of the sca-
