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108 MEMOIRS OF THE CARNEGIE MUSEUM 
anterior, are less emarginate, which gives to the manubrium of the former genus a 
less striking appearance. 
The first segment of the mesosternum has a curious structure. It is compressed 
laterally and its vertical is much greater than its antero-posterior diameter. The 
side view shows a (-shaped outline with the straight border behind. ‘The segment 
is expanded on its borders, those behind being the heaviest. The antero-posterior 
Fic. 66. (1) Lateral View of Sternum. (2) Inferior View of Sternum. Type of D. hollandi Peterson. } nat. size. 
diameter of the bone is slightly greater ventrally than dorsally. The bone differs 
greatly from that in Archxotheriwm ingens which has a relatively greater diameter 
vertically and a more angular outline laterally. The following two segments in the 
sternum of Dinohyus are codssified and their vertical diameter rapidly decreases, while 
their transverse diameter increases. ‘The transverse diameter of the dorsal border is 
twice that of the ventral, and the posterior face of the fourth segment very suddenly 
expands laterally. The succeeding two segments of the mesosternum are broader 
than deep and the last segment is the broadest and shallowest. The dorsal face is 
considerably broader than the ventral and the last two segments are slightly concave 
both dorsally and ventrally. The posterior border of the last segment is injured 
by. erosion, but the suture separating the following segment (xiphisternum) 
is plainly indicated (see fig. 66, No. 2). ‘The sternum as a whole is not unlike that 
of Archeotherium, but it possesses a proportionally smaller antero-posterior diameter, 
which seems to indicate that the thorax of Dinohyus was relatively shorter. 
Sternal Ribs. — There were four ossicles found with the sternum which are 
evidently the sternal ribs. hey are much enlarged at one end and taper rapidly 
to the other (the attachment for the sternum) and have rugose faces for a heavy 
cartilaginous covering. 
