HOLLAND AND PETERSON: OSTEOLOGY OF THE CHALICOTHEROIDEA. 333 
scapula has reached complete development. The posterior border is gently con- 
cave from the glenoid cavity to a point nearly opposite the middle of the spine, 
where the border becomes thickened and rugose, rounding outwardly and upwardly 
to the suprascapular border. The latter is quite heavy and gently rounded from 
before backward. The anterior border has a thin sharp edge, running in nearly a 
straight line, parallel to the spine from the anterior upper angle for all of two- 
thirds of the length of the bone, and then curving inwardly, showing a deep emargi- 
nation above the nodule of the coracoid. The prespinous portion of the blade 
agrees in its form and relative extent with what is found in such forms as Cenopus 
and Titanotherium. The posterior border of the scapula resembles more nearly 
that of Cenopus tridactylus than of Titanotherium, terminating usually in an evenly 
rounded posterior angle, as in the former, and not in a prominent, heavy, and 
rugose angle, as in the latter. However, in M. maximus the outline of the posterior 
border tends somewhat to recall the form which is characteristic of the titanotheres. 
The glenoid cavity is quite large, subcircular in outline, but not very deep. The 
spine, especially in old individuals, is as prominent as in Titanotherium, and its 
crest is reflexed and has nearly as heavy and rugose a surface for muscular attach- 
ments as in the latter genus. The inner aspect of the scapula presents a broad and 
gently concave surface, which in old specimens is broken by ridges for tendinous 
insertions. 
The foregoing description applies to the scapula of M. elatus, but in the case 
of,the corresponding bone in M. petersoni we observe that the width in proportion 
to the height is less, and that the rugose surface of the crest of the spine is narrower, 
and not so greatly extended backward. In the scapula of M. maximus the back- 
ward extension of the crest of the spine is not located at the middle of the crest as 
in M. elatus and M. petersoni, but at its lower extremity (see Fig. 77), thus giving 
the bone quite a different facies from that presented by the same element in the 
other two species. 
MEASUREMENTS OF SCAPULA. 
No. 1604 No. 1700 No. 1776 No. 1765 
(elatus), (petersoni), (maximus), (sp. indet.), 
mm. mm. mm. mm. 
eerie dtc ape, ebook aime cle aie Bie i One ere SSA a De ER i oa 528 423 593 323 
Greatestawithmeaei es ary eer iret cies Weir c eh See tec no Ss 327 240 460% 175 
Wc tno faire ckaanepaen tee eae rere at Sin a aera ys 5h uk. Uy 109 80 170 60 
Antero-posterior diameter of glenoid cavity................. 104 75 137 72 
Transverse diameter of glenoid cavity...................... 103 80 poet 62 
Vertical diameter of coracoid process....................... 49 35 62 35 
Greatest height of spine above blade..... EPS a aicas Ae EMS 93 80 133 55 
Greatest width of thickened edge of spine.................. 57 32 88 15 
50 Conjectural. 51 Badly crushed. 
