PAL^OSYOPS LEIDY, AND ITS ALLIES. 
351 
and not as angular as in the genus Telmatotheriuni. The buttresses of the molars 
are not so strongly developed as in the latter genus. In both species of Limnohyops 
the molars are without external cingula. On the true molars both intermediate 
tubercles may be fully developed in one species, while in the other they are much 
less so. The internal cones of the molars are angular and may be connected with 
the external V’s by slightly marked transverse ridges. In the last superior molar 
the hypocone may be large and equal to the height of the protocone, or reduced and 
much smaller than the protocone. 
Skull. — The skull is mote elongated and primitive in form than in Palceosyops. 
From above downward it is much depi’essed, especially so in L. fontmalis. The 
facial portion of the skull is short in comparison with the much elongated cranial 
part. The nasals ai’e long, narrow and of the same width throughout. The 
premaxillary bones resemble closely those of Palceosyops, being short and com- 
pressed, with a small round symphysis. The occipital crests may be greatly devel- 
oped, much more so than in any other genus of this subfamily. The auditory pro- 
cesses are distinct and the zygomatic arch is broad and heavy. The brain was 
probably very small and much less in bulk than in the allied genus Palceosyops. 
The Skeleton . — Portions of a skeleton which 1 believe to belong to this genus, 
show the following characters in addition : The scapula is more slender than 
in Palceosyops, with its spine oblique to the plane of the glenoid cavity. Bones of 
arm and forearm more slender than in Palceosyops. Carpus highly specialized, the 
lunar having the magnum facet nearly vertical. Magnum high and narrow. A 
large contact between the nietacaqjal III and unciform. Carpus more nearlj^ of the 
mesaxonic type than in Palceosyops. Fifth metacarpal well developed. Tarsus 
more elongate and slender than in Palceosyops ; facets of astragalus and calcaneum 
continuous. There may be a contact between the cuboid and metatarsal III. There 
are only two species of this genus at present known ; their characters are given in 
the following table : 
Synopsis of the Species of the Genus Limnohyops. 
A. Size large. 
Hypocone of superior molar III one-half the size of jirotocone, L. laticeps. 
B. Size small. 
Hypocone of last upper molar equal in size to protocone, L. fontinalis. 
Limnohyops laticeps. 
(Syn. Palxogyops laticeps Marsh, Limnohym laticeps Leidy.) 
The description given by Prof. Marsh" of the dentition of this species is exceed- 
ingly brief, and he fiiils to point out some of its most important dental characters. 
Dr. Leidy," in his report for 187o, figures a superior molar which he, correctly I 
think, refers to P. minoi' (his P. paludosus in part), but having consulted Prof. 
*Am. Jour. Sci. and Arts, 1872, page 2. 
"Rep. U. S. Geol. Surv. of Ter. for 1873, Plate XXIII, fig. 13. 
