MCERITIIEEIUM. 
117 
be regarded as a free sacral rather than as a caudal. The centrum is depressed, and its 
ventral face only slightly convex from side to side, ])assing externally into the broad 
transverse processes. The anterior end of the centrum is convex, and slopes somewhat 
forwards; the posterior end is much higher in ])roportion to its width: this vertebra 
is, in fact, intermediate in form between the sacrals and caiidals. These latter are not 
known in the present specimen, but in another, much less nearly com])lete, column 
several are preserved. Their centra are laterally compressed, particularly behind, so 
that while the anterior face of tlie centrum is nearly circular, the posterior is a vertically 
elongated oval. The neural arch seems to have been confined to the posterior half of 
the centrum. There are short downwardly directed transverse processes towards the 
anterior end. Posteriorly the ventral border bears facets for chevrons, which, in some 
cases at least, were V-shaped. 
Fore Limb . — The scapiila, the humerus, and the proximal portion of the ulna only 
are known. No complete specimen of the scajnda has yet been found. The best 
example (from the left side) is figured in PI. XI. fig. 5. The glenoid cavity {g.c.) is 
oval in outline, and the articular surface is continued forwards on to the posterior 
surface of the large and prominent coracoid process (c.). Anteriorly this process bears 
a rough ridge, which passes above into the coracoid border (c.b.). This border is 
concave below, but is incomplete above ; it seems, however, to have curved forwards so 
that the upper part of the blade was wide. The glenoid border (g.b.) is gently curved 
backwards; the suprascapular region is broken away. The spine (s.) originates 
about 2‘5 cm. from the glenoid cavity; it forms a prominent backwardly inclined 
flange, parallel with the glenoid border ; it cannot be seen whether or not there 
was an acromion. The postscapular fossa is narrow but deep, and overhung by the 
spine ; the prescapular fossa is wider and more open. This scapula, in the backward 
sweep of its blade, presents some approach to the Sirenian type, and in the large 
size of the coracoid process and the form of its coracoid border is similar to the 
scapula of Barytherium described below. 
In the humerus (PI. XI. fig. 6) the head (h.) projects strongly backwards and inwards ; 
it is much more strongly convex from before backwards than from side to side. The 
greater tuberosity is large and rises to about the same level as the head. Externally 
it is flattened, internally it forms the outer border of a broad bicipital groove, the inner 
side of which is formed by the small but still well-defined lesser tuberosity. The 
shaft is chiefly remarkable for its extreme lateral compression. The narrow flat anterior 
surface is continuous above with the flattened face of the greater tuberosity ; lower 
down it passes into the inner face of the bone, its prominent outer border forming the 
deltoid crest [d.], from which a rounded ridge runs obliquely across the anterior face of 
the bone to the inner end of the distal articular surface, so that the whole bone when 
seen from the front appears to have a slight spiral twist. The inner condyle {i.c.) is very 
large and projects below the rest of the bone; it is not perforated by an entepicondylar 
