Page:Quarterly Journal of the Geological Society of London, vol. 26.djvu/121

1869.] 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, Iguanodon, Hypsilophodon, Hadrosaurus, and probably Stenopelyx 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.

2. Establishment of the Order 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. This group will contain two primary subdivisions: