THE ArA^iAr.VLTA of the uin^ta formatiox. 495 



Tlie hinnfras agrees closely with that of Oreodon, which, as Cope has pointed 

 out (No. 4. p. 508), is very peculiai- and difteiing from that of all recent artiodactyls, 

 finds its nearest analogue in Anoplotlierium. "'The greater tuherosity is large, rising 

 ahove the head; and is incurved, terminating inwards in an acuminate apex. Its 

 border at the base is thrown into an obtuse angle. The lesser tuberosity is small, and 

 is well separated from the gieater by a deep and wide bicipital gi-oove. The deltoid 

 ridge is distinct. The condylar extremity is more transversely extended than in any 

 recent artiodactyl, owing to the fact tiiat the posterior internal distal tube- 

 rosity is placed interior to the tiochlea instead of partially behind it, and that there 

 is, in addition, an iiiti'inal (.'picondyle not seen in the recent suilline or ruminant mem- 

 bers of the order. The intei'condylar I'idge is strong, and wider than in most recent 

 ruminants; in the suillines it has nothing like such a development. Another pecu- 

 liarity is the rtange-like free border of the exteinal trochlea, which is especially re- 

 curved at its superior part." With a few modifications this description will apply 

 equally well to the humerus of Protoreodon, The shaft is rather more slender and 

 the deltoid ridge much less massive and prominent; the anconeal fossa is narrow and 

 very deep, perforating the shaft, as is also genei-ally the case in the Miocene genus. 



The ulna, as would naluially be expected, shows no tendency to coossify with 

 the radius; the olecranon is unusually long and stout and deeply grooved at its upper 

 end; the sigmoid notch forms somewhat less than a semicircle and passes below into 

 two small facets for the head of the radius. The shaft is stout and trihedral in the 

 upper portion, but becomes very much compressed below and presents a deep groove 

 on the internal side. The distal end is not preserved in any of the specimens. This 

 bone shows more difterences from the corresponding element of Oreodon than does 

 the humei'us; the most important of these are the proportionately greater size of the 

 olecranon and the sinjjular llatteniny; and ":roovin<>: of the shaft. 



The radius differs but slightly from that of Oreodon, as far as tlie fragments pre- 

 served allow of comparison. The surface for articulation with tlic humerus is a 

 rather broad head, which is much compressed from before backwards; the articular 

 facets form three [)ortions, a median concavity for the intercondylar ridge, or tuber- 

 osity it might be called, and a more flattened sui-face on each side of this. The 

 external beveled surface for the curious flange on the humeral condyle above men- 

 tioned, is more concave and descends lower on the anterior far-e of the bone than in 

 Oreodon, and the anterior edge is somewhat more sinuous than in that genus, though 

 there is no emaigination for the intercondylar ridge, such as occurs in the anterior 

 proximal edge of the radius in the recent ruminants, and, in a much less marked 

 degree, in the suillines. This structure of tlu' head of tiu' radius is highly chaiac- 



