MUSEUM OF COMPARATIVE ZOOLOGY. 155 
skeleton of this species ; it is relatively lighter and more slender than in the 
larger species, but otherwise not different from it. Most important is a speci- 
men containing all the metacarpals and phalanges in undisturbed position, and 
this shows most distinctly the presence of the pollex, as one of us* had pre- 
viously shown to be true in the case of O. Culbertsont. This correspondence 
between the two species removes all suspicion that the pollex in the specimen 
first described might be a case of abnormal polydactylism. The discovery of 
a five-toed artiodactyl is of the utmost importance, as it furnishes the demon- 
stration of what has long been surmised, that the ungulates of both odd and 
even-toed series have been derived from pentadactyl forms. 
Eucrotaphus (Oreodon) major, Leidy (Eporeodon major, Marsh). This 
genus differs from Oreodon in the presence of large inflated tympanic bull, and 
also (fide Marsh t) in the absence of a pollex. The dentition and character of 
the skull are identical in the two genera. 
Agriochcerus latifrons, Leidy. Isolated jaws and teeth. 
SUIDA. 
Hyotherium (!) americanum, sp.nov. There is inthe Princeton Museum 
asuilline skull from the White River formation, which cannot be corre- 
lated with any of Dr. Leidy’s genera. It agrees very closely and is probably 
identical with the Hyotheriuwm ot Europe, and will be provisionally referred to 
that genus.. In the Cambridge collection there is a suilline hind foot, which 
may be referred to the same species. The astrggalus is very oblique, the 
external condyle greatly exceeding the internal in size ; the neck is short and 
the distal end broad ; the calcaneal facets are confluent. The cuboid is low, 
broad, and deep (antero-posteriorly). The metatarsals are very suilline in 
character, the median pair short and massive, the laterals shorter and espe- 
cially more slender ; the proximal ends are all on the same transverse line, and 
the articular faces nearly plane ; the trochlear ridges on the distal ends are 
confined to the posterior aspect, thus differing from Sus, Dicotyles, and other 
recent genera. The phalanges of the median digits are heavier but not much 
longer than those of the lateral digits. 
MEASUREMENTS. 
Astragalus, length (outer side) .) -: --. 5 « « + 2 © 6 032 
eS GIRLIE ETOCMI CR as noes 54) Boe et eh oe eee Oe 
Brita PELE Be Se) eee oes. > Sar. aiopi B al et a Oe ee eee 
SAMMI IGIR ai i Ie og. “o, “nip ali lore ens og ey eee Bee 
ESATO UE MORE ays spa bs. wy ky ef ed ee ee ORO 
ee 10 Se Sigel ca 8/2) aCe ete ooh adey ete 
* Scott, Proc. Am. Ass. Adv. Sci., 1884, p. 493. 
+ Dinocerata, p. 187, fig. 162. 
