124 MEMOIRS OF THE CARNEGIE MUSEUM 
in the American forms, and had a somewhat similar though less prominent contact 
with Me. III, as in Sus. In Anthracotheriwm, the general similarity of Me. III 
(Paleeontographica, Vol. X XII, p. 308, Pl. XIII, fig. 80) to that of the Entelodontide 
is quite striking, as Scott has pointed out, butit ‘‘is relatively heavier; at the prox- 
imal end the tubercle for the insertion of the extensor carpi radialis muscle is more 
conspicuous, and the palmar projection of the head more prominent.” ‘To this 
might also be added that the facet for the trapezoid is apparently indicated, which is 
naturally to be expected in a tetradactyl form, although Kowalevsky does not 
mention it. 
MEASUREMENTS. 
Type No. 1594, No. 2136. 
Mm. Mm. 
Metrearpalbinl, sreatest:leng thier sven (inc.citins visi betes ca ty denas 240 
ee ‘« antero-posterior diameter, proximal end........... 57 58 
fe ‘¢ transverse ce ve Oh rh sgtes ieee JOT 65 
Ef ‘« antero-posterior ue distal end .. 45 46 
x “« transverse wy oy ic . 54 55 
Metacarpal IV. — The fourth metacarpal is complete in the type, and, as in the 
earlier forms of this family, smaller than the third. There are two articulating 
surfaces on the proximal face, one for the unciform and the other for Mc. III. The 
former is large and nearly triangular in outline ; the latter has a wedge-shaped out- 
line with the apex directed posteriorly. On the radial side are two facets, one dorsal 
and the other palmar; the two articulate with Mc. III. On the radio-palmar angle 
is a third facet of small size, which supports a palmar sesamoid (see fig. 70). On the 
ulnar side there is a prominent process, which has a round articular surface for Me. 
VY. The shaft has the greatest constriction immediately below the head and gradu- 
ally becomes wider distally. There is no essential difference in the distal trochlea 
from that of Me. ITI. 
MEASUREMENTS. 
Type No, 1594, No. 2136, 
Mm. Mm, 
Metacarpal IV, greatest length . 215 220 
¥s “antero-posterior diameter, proximal end 58 56 
ze “transverse iy Se Oe are ean te 62 63 
os ‘« antero-posterior diameter, distal end............... 44 45 
e ‘« transverse & ee ens wansteeedeaeres 55 57 
Metacarpal V.— The fifth metacarpal is a rudimentary almond-shaped sesamoid 
which is of about the same proportionate size as that in Archxotheriwm.”  Proxi- 
mally there are two distinct articular surfaces: a superior one for the unciform, and 
an inferior one for Me. IV. 
52 The fifth metacarpal in Bodcherus humerosus from the John Day formation is apparently of greater size and 
also longer than in Dinohyus. 
