174 
TEHTIATiY VEKTEBEATA OF THE FAYCtM. 
it lias four roots. M. 2 is Bilojihodoiit ; it is somewhat longer than broad. M. 3 
(IM. XVII. iig. 0) is also bilo])hodout, with a talon; the anterior crest is slightly 
concave forwards, the shorter jiosterior one nearly straight. There seems to have 
been a small accessory cusp in the valley between the main crests, and another on 
the antc'i'ior border of the tooth ; in wear these become united with the inner ends 
of the ))osterior and anterior crests respectively. 4'here are only four roots to this 
tooth, the ]iostero-internal one being enlarged to support the talon. 
Fore Limb . — The scapula (PI. XVII. figs. 9, 9 a) is not completely known, the best 
specimen wanting the upper portion. The prescapular fossa is very small, the post- 
scapular large and regularly concave from side to side. The spine (s.) commences 
some distance above tlie glenoid surface and rises very rapidly ; its greatest height, so 
far as preserved in the specimen here described and figured, is about 7 '5 cm. The 
coracoid border (c.b.) is thin and sharp above, but thickens rapidly below, where it 
passes into the great tuberous coracoid process (cor.). This seems to be larger than 
in any other mammal, forming a massive hook-like process overhanging the glenoid 
cavity, the articular surface of which appears to have been continued for a short 
distance on its posterior face. On its inner side it is raised into a prominent ridge, 
sepaj'ated fj om the border of the glenoid cavity by a groove. The glenoid border 
is marked off from the actual edge of the glenoid cavity by a slight notch, above 
which it is thickened and rounded, thinning, however, very rapidly upwards. The 
large glenoid cavity proper (f/.c.) is nearly circular in outline, but, as already mentioned, 
the articular surface is continued forwards on the coracoid process ; the articular 
surface (fig. 9 a) is nearly fiat from side to side and concave from before backwards. 
4'he dimensions of this scapula are given below. 
Two specimens of the humerus are known, one, though otherwise imperfect, exhi- 
biting the whole length, while the other (PI. XVII. figs. 7, 7 a) includes the distal 
three-quarters of the bone in almost perfect condition with exception of the 
articular surface. The chief peculiarity of this humerus is the enormously massive 
distal extremity, the condyles especially being greatly developed. The trochlear 
surface is divided into two nearly equal portions by a comparatively shallow groove 
which runs obliquely outwards and forwards, so that the articulation a])]icars some- 
what oblique. There is a very large and deep coronoid fossa (c.f.) and a deep though 
much smaller and more sharply defined olecranon fossa (oLf.), but the two do not 
appear to have communicated with each other. The outer condyle (o.c.) is a great 
mass of bone, of which the posterior flattened surface forms the outer wall of 
the olecranon fossa. The outer face is also flattened and looks outwards and 
downwards. From its upper end the siqiinator ridge (s.r.), forming a prominent crest, 
runs upwards and backwards. The inner condyle (i.c.) is also very prominent ; below 
it seems to be separated from the trochlea by a dec}) notch ; anteriorly it is hollowed 
into a pocket-like fossa which is sharply defined by a ])rominent ridge below, hut above 
passes gradually into the antero-iiiternal face of the shaft. The deltoid crest {(/.) 
