Quadrate. The smallest specimen is 1/2 an inch over the articular surface for the lower jaw and a quarter of an inch thick. It is concave from side to side in front where it shows a large pneumatic foramen near the basal end; it is bent from the articulation a little backward. It is convex behind; and between the foramen and the articulation sends inward and forward a great wing like that of the quadratum in birds. The specimens are broken short off and do not show any articulation above, where the bone contracts.

The distal articulation is double, like two long cones placed together; that in front having the base outward, while the hinder one has the base on the inner side. The largest specimen, which is much broken, shows the articulation half an inch thick.

Quadrato-jugal. This is a thin flat squamous bone, apparently of a transverse diamond shape, which is anchylosed to the anterior lateral margin of the quadrate, at right angles to the articulation. The lower margin is straight, as is the upper anterior margin, which appears to have received the malar bone above.

The upper posterior side is broken, but shows a large foramen near to the side of the quadrate. The base of the diamond is at the articulation, and at its apex is a small fragment of smooth surface, either part of a foramen, or the orbit of the eye.

In this specimen the articulation, which is broken, is about 3/4 of an inch wide, 3/8 of an inch thick. The remaining piece of the quadrate is an inch long. The quadrato-jugal is an inch and 3/16 high, and between its broken ends 13/4 inch long. It is thick and strong where joining the quadrate, but the rest of the bone is about an 1/8th of an inch thick.

The quadrate bone is Avian in possessing a pneumatic foramen, and Avian in the form of so much of the distal end as is preserved, and in the articulation for the lower jaw. The process which it sends inward on the inside is probably for the pterygoid bone, after the manner of Birds. Before anchylosis with the quadrato-jugal bone set in, as may be seen in J.c.11.4, the union was made by a hemispherical knob on the outside of the quadrate, as in Gallus domesticus. The squamose quadrato-jugal is a distinctive character.

Case.Comp.Tablet.Specimen.
Jc141—2

?PTERYGOID END OF PALATINE BONE.
[Pl. 12.]