AND CLASSIFICATION OF THE FOSSIL IlEPTILIA. 
257 
Coracoid Bones of an Anomodont. (Plate 15, figs. 5, 6.) 
A specimen numbered 3G,286 consists of a pair of coracoids. On the ventral surface, 
stretching in a line at right angles to the anterior margin of the left bone, are four 
dorsal vertebrse, a good deal flattened and distorted, which extend, as preserved, over a 
space of about 8 centims., but they lie about half a centimetre apart, each centrum 
being ] ‘5 centim. long. 
I presume that the pre-coracoid joined the straight suture on the anterior margin ; 
that the inter-clavicle joined the internal inai’gin, which is exceedingly thin; and the 
thicker posterior margin joined the &ternum. The bone has a thickened ovate external 
articular area, 3 centims. deep and 2 centims. wide, which gave attachment to the 
scapula by a large surface, and contributed with it to form the glenoid articulation for 
the humerus. In form it may be regarded as a segment of a circle, with the convex 
border facing toward the inter-clavicle, and the humeral articulation forming the 
narrow border toward the centre of the circle. The greatest transverse width of the 
bone is about 6'3 centims. The greatest antero-posterior extent is 7 centims. The 
internal border is regularly convex from front to back ; it is thin, not more than 
4 millims. thick in the middle, but becomes about a centimetre thick at the posterior 
extremity. This thickening is seen on both sides of the bone, and it helps to define the 
concave visceral surface of the iriternal aspect, as well as a slight concavity on the 
posterior part of the external aspect, besides giving rise to a flattened oblique posterior 
area a centimetre wide, which looks backward, outward, and upward. The extreme 
measurement from the posterior extremity of the bone to the humeral surface (in a 
straight line) is 5‘5 centims., but the posterior outline of the bone is concave, forming a 
wide arch behind the articular surface for the humerus, with the contour straightening 
as it extends backward, and ultimately rounding convexly on to the internal margin 
of the bone. 
The nearly straight anterior margin of the bone is less than 4 centims. long. 
Immediately behind the articular surface is the pre-coracoid notch, about half a 
centimetre wide and nearly as deep, which contributed the posterior border to a 
foramen, paid of the contour of which was formed by the pre-coracoid, and part by the 
scapula. The straight anterior sutural border is narrow, transverse to the axis of the 
bone, concave on the visceral surface, convex externally, 7 millims. thick. At this 
notch the extent of the bone from front to back is about 3 centims., and at the 
articular surface it measures a few millimetres more. The anterior and superior pari, 
of the surface gave attachment to the scapula, while the ovate postero-inferior surface 
was for the humerus. 
2 L 
MDCCCLXXXIX. —B. 
