2. The anterior prolongation of the ilium is more slender than the posterior.
3. The rami of the mandible unite in an excavated edentulous symphysis, which receives an edentulous prolongation of the præmaxillæ.
4. The proximal end of the femur is as in the Scelidosauridæ.
5. There is no dermal armour.
Cetiosaurus[1], Iguanodon, Hypsilophodon, Hadrosaurus, and probably Stenopelyx[2] belong to this division.
These three groups appear to me to be very well marked; but I do not propose them with the intention of suggesting that there are no others, or that the progress of discovery will leave them thus well defined.
The very remarkable reptile, Compsognathus longipes, has many affinities with the Megalosauridæ, Scelidosauridæ, and Iguanodontidæ, but it presents, at the same time, so many differences from all these, and so much of its structure is left unrevealed by the solitary specimen which exists, that perhaps the most convenient course which can be adopted, at present, is to make it the re- presentative of a group equivalent to them. Compsognathus differs from all the preceding forms in the length of the cervical relatively to the thoracic vertebræ, and in the femur being considerably shorter than the tibia[3].
2. Establishment of the Order Ornithoscelida to include the Dinosauria and the Compsognatha.
But Compsognathus agrees with the Megalosauridæ, Scelidosauridæ, and Iguanodontidæ in the ornithic modification of the Saurian type, which is especially expressed in the hind limbs; and I therefore propose to unite it with them in one group, which I shall term Ornithoscelida. This group will contain two primary subdivisions:
- ↑ I assign this place to Cetiosaurus on the evidence of the splendid series of remains of this reptile which Prof. Phillips showed me in the Oxford Museum.
- ↑ Von Meyer has described a reptile from the German Wealden, in the 'Palæontographica' for 1859, under the name of Stenopelyx Valdensis. Only the pelvis, a few vertebræ, and the left hind limb of this very interesting genus are preserved; but they suffice to prove it to be a Dinosaurian. There are four digits in the foot, the fifth being absent, while the hallux is smaller than the others. The fibula is slender; the tibia stout and apparently as long as the femur, the head of which is at right angles with the shaft. The ischia are in place and longer than the femur; they are stouter in proportion than in Iguanodon or Hypsilophodon, and quite differently formed. What Von Meyer regards as the pubes are, if I mistake not, the anterior prolongations of the ilia.From the absence of any dermal armour, one would be disposed to arrange Stenopelyx among the Iguanodontidæ; but many of its characters are very peculiar.
- ↑ Professor Cope has distinguished Compsognathus as the type of a division, Ornithopoda, from the rest of the Dinosauria, which he terms Goniopoda. The Ornithopoda have the astragalus ankylosed, while in the Goniopoda it is free. But there is much reason to believe that the astragalus became ankylosed in some of the "Goniopoda;" and it seems to me precisely by the structure of the foot that Compsognathus is united with, instead of being separated from, the Ornithoscelida.
