Page:Quarterly Journal of the Geological Society of London, vol. 25.djvu/517

 like manner, the lower ones coursing parallel to this border, while the upper lines radiate towards the coronoid process. The angular bone forms the lower half of the hindermost 16 inches of the ramus, and completes the posterior extremity. It composes the whole lower border of the ramus for about 25 inches, and it is also visible on the inner surface, below the articular bone, from which in this situation it is marked off by a suture, which, further forwards, a couple of inches in front of the salient anterior internal angle of the articular bone, becomes lost in the matrix. In the outer surface a conspicuous suture, nearly straight for the first 9 inches from the posterior extremity, and then curving downwards for the next 15 inches, separates the angular bone from the dentary and surangular bone above it. The anterior two-thirds of the angular bone are also longitudinally striated ; and the uppermost striae run out obliquely at the upper border of the bone, which helps to increase the distinctness of the suture between it and the surangular. On the inner side, the anterior internal angle of the articular bone projects strongly 3 inches above the lower border of the ramus, and nearly 6 inches from its posterior extremity ; its anterior margin descends at first almost vertically, and then curves forwards to the suture with the angular bone. In front of this the inner surface is hidden for nearly 4 inches by large splints of bone lying athwart it, which are, I think, pieces of the upper jaw*; and for 6 inches in front of these it is much defaced ; but beyond this, to the dental part, it is smooth, and channelled by a broad, shallow, longitudinal groove. The splenial bone is wanting.

The piece of the lower jaw lent me by J. C. Mansel, Esq., consists of 7 inches of the anterior extremity of the right half. The lower and upper lines meet in rather a blunt point. The outer surface, transversely convex, is beset with a few vascular foramina below the two first alveoli. The inner, vertical surface is scored with marks of the symphysial suture. The upper surface is horizontal and flat, rising slightly towards the inner border ; its outer third is pierced by the openings of six sockets, from the four last of which fully grown teeth protrude. The sections which Mr. Mansel has most kindly allowed me to have made†, show clearly the loose implantation of the long tooth- fangs in capacious alveoli, which have a forward and outward inclination that gives a corresponding slant to the teeth. The alveolar apertures in the border of the dentary bone are quite distinct from one another. They are here separated from each other by very evident unbroken partitions, which, however, are less complete in the in-

they are portions of both maxillae crushed and retroverted, so that the front end overhangs the posterior extremity of the ramus of the lower jaw. The nasal bones are absent ; but the groove into which they were received reaches forwards for a considerable distance on the upper and inner edge of the maxillary bones.
 * These splints have been further exposed since the above account was written ;

† For getting these sections made I am under great obligation to Mr, Etheridge.