52 MEMOIRS OF THE CARNEGIE MUSEUM 
ent writer was recently able to carefully study the type and the other material referred 
to A. crasswn by Marsh. My observations are of some interest in this connection, as 
they serve to further characterize this species. I at once detected that the premaxilla- 
ries are long, as is usual in the species from the lower Oligocene, the preorbital foramen 
is above P~ and is of large size, the orbit is rather low, and has the anterior border 
opposite the posterior part of M2. The downward projecting process of the jugal is 
directed rather more forward than backward and terminates in an enlarged and some- 
what oval free end; the zygomatic process does not quite reach the anterior border 
of the glenoid cayity. Pz has a characteristically limited antero-posterior diame- 
ter. Py and Py are abruptly reduced as in A. coarctatwm Cope, and the anterior 
tubercles of the molars are quite high, as in that species. The superior molars are 
yet buried in the matrix, so that nothing more can be said regarding their charac- 
ters, than that they have apparently an- 
terior and posterior cingula, as usual, but 
are externally almost smooth. 
There are only a few fragments of 
vertebree with the type. Portions of left 
arches of two dorsal vertebrae show perfor- 
ations of large foramina at the base of, and 
immediately posterior to, the transverse 
processes, but in neither of the two arches 
are there any indications of vertical canals 
as in Dinohyus, 
The limbs of the type specimen are 
very fragmentary; there is no scapula. 
The great trochanter of the humerus is 
very prominent and terminates superiorly 
above the head in an enlarged and trun- 
cated end, directed backward and with the 
yrocess of the lesser tuberosity nearly en- 
y y 
closing the bicipital groove. The inter- 
Fig. 8. Side and Upper View of Skull of Archao- trochlear ridge is prominent and the ex- 
therium crassum Marsh. } nat. size. (After Marsh.) age as Ee 
ternal condyle is narrow. The internal 
epicondyle is relatively prominent. ‘The calcaneal facet of the cuboid is broader than 
that for the astragalus. Mt. IV is complete and measures 155 mm in length. Mt. 
V was of relatively large size, judging from the facet for it on Mt. IV. The meta- 
J (=) ? to) 
podial as a whole is rather delicate and the cross-section of the upper half of the 
shaft has a square appearance. 
