HOLLAND AND PETERSON: OSTEOLOGY OF THE CHALICOTHEROIDEA. 193 
In October, 1907, the writer visited the locality and made a careful exami- 
nation of the spot and determined that the work of exploration should be further 
continued during the season of 1908. 
In the spring of 1907 the material representing the large specimen of Moropus 
had been freed from the matrix and an effort was at once made to carefully study 
the specimen. It was gratifying to discover that enough had been recovered with 
the exception of the cranium and the caudal vertebre to allow an almost perfect 
restoration to be made. It is true some of the bones were broken and required 
minor repairs, and a few were lacking, but there was enough in almost all cases 
to show plainly what was defective, and where one side of the skeleton failed to 
give light the other supplied it. In addition the specimens recovered by Mr. 
Utterback from Quarry No. 2 were sufficiently numerous in some cases to supply 
perfect specimens representing the missing portions of the larger skeleton; so 
that in the light of these it was possible with absolute certainty to restore the 
outlines of missing fragments. 
In August, 1907, Mr. Peterson with the consent of the writer read before the 
International Zodlogical Congress at its meeting in Boston a brief paper upon the 
anatomy of Moropus, based upon the material which had up to that time been 
recovered, which marks a distinct advance in our knowledge not only of the genus 
Moropus, but of the osteology of the Chalicotheroidea in general. 
In the spring of the year 1908 Mr. O. A. Peterson returned to the familiar 
spot, being earnestly requested to make every effort to secure a complete skull of 
Moropus. With the assistance of a number of able workmen he stripped the 
western side of the butte on which the work of the Carnegie Museum had already 
been carried on during the three preceding years, beginning near the point in 
Quarry No. 1 where Mr. Utterback had ceased operations. Although finding 
an abundance of the fossil remains of other mammals, Mr. Peterson only recovered 
a few scattered fragments of Moropus. He was on the point of despairing of 
success in his quest, when, as a last resort, he gave instructions to the workmen to 
enter the side of the hill at the place where Mr. Utterback had recovered the most 
of the remains of the large specimen taken up in the fall of 1905 and in the summer 
of 1906. Mr. Utterback had reported that he had gone into the side of the hill 
at this spot far enough to satisfy himself that the bone-bearing stratum, to use 
his expression, had “‘played out,” and to all appearances his report was correct. 
At the point where he had stopped work no bones were visible. The men digging 
under the direction of Mr. Peterson had only gone about two feet into the side of 
the rock when to the great delight of all parties a nearly complete cranium (No. 
