THE CAMBRIDGE GREENSAND. 609 
directed a little backward. The base is better defined by an obscure 
angular ridge, and midway on the side, below the transverse pro- 
cess, is another angular ridge. The articular ends of the centrum 
are more concave than in the earlier vertebre. ‘The first six ver- 
tebree (fig. 5) are in natural sequence; then the series is broken by 
the loss of probably four vertebrae. The remaining two centrums 
preserved were followed by at least four more, so that the tail may 
have included at least sixteen vertebrae, and have measured at least 
as many inches. 
The last centrum preserved has the anterior face $9 inch wide and 
4% inch deep, with the outline flattened above and convex below. 
Lhe posterior face is ;®; inch wide and ;8; inch deep. There is an 
indication of division in the chevron facets. ‘The underside of the 
centrum becomes rounded, and the size of the transverse process, 
still high on the side, is reduced to a mere tubercle. The neural 
canal is narrow and slightly channelled in the centrum, and the base 
of the small neural arch was less than ;4, inch long. 
Tur Scaputar ARCH. 
Coracoids.—The right coracoid is only preserved in a fragment, 
but the left is fairly perfect (Pl. XXXV. fig. 2). It was an ex- 
panded subquadrate bone of the usual pattern, thick at the articular 
surfaces for the humerus and scapula, and thin at the two other 
edges, the anterior and upper of which is broken. The underside 
of the bone is concave, the upperside gently convex. It is 3,4, inches 
wide from the scapular to the inferior margin. The surface to which 
the scapula was attached (fig. 2, 6) is convex in length, as preserved, 
and imperfectly ossified. It measures about 13 inch in length, is 
1,4, inch thick at the junction with the humeral surface, and becomes 
compressed asit ascends. The humeral surface (fig. 2, a) is subquad- 
rate, 1,2, inch long, and of about the same thickness ; it is smooth, 
truncating the bone transversely, and nearly flat. Below the humeral 
articulation the bone is emarginate on the external surface, and the 
emargination resembles the appearance that would be produced by 
drawing the thumb over the angle of a plastic substance. The por- 
tion of the anterior border which looks downward is 24 inches long, 
as preserved, and thin, thickest at the corner nearest the humerus, 
and becoming attenuated as it ascends. The other upperside, which 
is somewhat broken, is about 21 inches long. The coracoid foramen is 
placed about the middle of the scapular margin, and extends obliquely 
inward, upward, and backward ; it is about =3, inch in diameter, and 
penetrates into the scapular margin as it emerges on the inner side 
of the bone. 
Scapula.—The scapula is known from an important fragment, 
comprising the articular end of the right side of the bone (Pl. XX XY. 
fig. 3). It is imperfectly preserved at the anterior border, but is 3 
inches wide. The humeral surface (a) is flat, 13 inch long, and about 
as wide ; it is rounded posteriorly, and convex on the inner surface 
from side to side, The coracoid surface (¢) is divided into two por- 
tions, and is somewhat compressed from side to side. The inner 
surface of the bone is concaye from above downward. The pos- 
