324 MEMOIRS OF THE CARNEGIE MUSEUM. 
In addition to the material above enumerated there are more or less frag- 
mentary portions of the ribs of other individuals collected in the summer of 1908, 
which have not as yet been removed from the matrix, and upon which no report 
can at present be made. 
Moropus possessed fifteen ribs on each side, of which the first is the shortest. 
The ribs gradually increase in length from the first to the eighth, which is the 
longest, and gradually decrease in length from the eighth to the fifteenth. The 
first three anterior ribs have a less convex external curvature than the others, 
but the curvature rapidly increases posteriorly and reaches its maximum develop- 
ment in the four posterior ribs, the curvature in which is very nearly the same. 
All of the ribs except the fifteenth show at their end provision for the attachment 
of cartilages. The fifteenth rib was free. The capitulum the faces of which always 
coalesce is carried in the case of the anterior rib upon a long neck; the length of 
the neck decreases as we go backward along the series to the third, and then in- 
creases to the sixth, after which it gradually diminishes until we reach the thirteenth 
rib, where the capitulum and tuberculum fuse with each other. The fourteenth 
and the fifteenth ribs retain only vestiges of the angle in the form of a slight swelling 
below the fused capitulum and tuberculum. 
In comparing the ribs of Moropus elatus and Moropus peterson we discover, 
as might be expected, that the ribs of the latter are not as massive or as heavy 
throughout, the animal being smaller. 
The Farst Rab. 
The first rib is short, flattened, broadest at its extremity; the capitulum is 
supported upon a relatively long neck, strongly constricted before the tuberculum, 
the axis of which forms approximately a right angle with the axis of the shaft. 
Measurements (No. 1604). 
Mm. 
Length of first right rib. Measured in a straight line from top of capitulum 
to-outer angle.ofeShatt.. owe. pean eh ene ea ee eae 276 
Diameter of upper portion including head........ a ee Men ers eral a relase \o 81 
Greatest diameter of shaft near the middle............................-: 42 
Greatest diameter of shaft near end, estimated......................--05: 66 
The Second Rrb. 
The second rib is a little more than one-third longer than the first rib. It is 
flattened in its lower two-thirds, somewhat wider just beyond the middle than at 
the end. The neck supporting the head is only about half as long as the corre- 
sponding portion of the first rib, 
