352 MAURICE G. MEHL 
attachment of muscle. The stout shaft is oval in section; its anterior border 
bears a roughened ridge, and the upper part of its ventral and ventral-posterior 
surface is roughened for muscle attachments. Distally the bone is expanded 
and compressed from above downward. ‘The facet for the radius is the largest, 
that for the pisoform the smallest; the surface of the accessory ossicle is situ- 
ated entirely on the postaxial border nearly parallel with the long axis of the 
bone. 
The material at hand consists of the left humerus, the radius, 
five carpals, and a sixth bone which is probably a supernumerary 
epipodial. To the description of the humerus by Professor Knight 
it might be added that the plane of the distal expansion forms an 
angle of about fifty-five degrees with that of the head and tuber- 
osity and that there is an articular face on the posterior distal end 
for the articulation of a third bone and perhaps a fourth facet on 
the posterior face of the expansion. ‘The arrangement of the carpal 
bones is quite certain, there being three in the proximal row and two 
in the distal row, with a third, the first distal carpal, missing. A 
sixth bone, the position of which is uncertain, is represented in 
the figure by an unshaded outline as articulating with the humerus 
and the third carpal in the proximal row. There seems to be a dis- 
tinct facet on the humerus and carpal at these points and in all 
probability the bone represents a supernumerary epipodial. 
One of the most striking resemblanees between the two forms is 
seen in the posterior border of the humerus; in each the distal 
expansion is recurved posteriorly, and although the fourth bone 
found articulated with the humerus of T. seeleyi is absent in 
T. laramiensis, the posterior border of the humerus suggests that 
such a bone was originally present though perhaps not thoroughly 
ossified. A comparison of Figs. 2a and 2b shows this likeness. 
I take this opportunity to acknowledge the kindness of Pro- 
fessor Reed in granting me the privilege of studying this material 
and also to thank Dr. Williston for suggestions in the preparation 
of this paper. 
