PALJSOSYOPS LEIDY, AND ITS ALLIES. 
367 
cuboid in the former species has a straight internal border, wliereas in L. laticeps 
this border is round. 
Metatarsals . — The metatarsals agree in many of their characters with those of 
Hyrachytis, hut they difter from them in being longer and broader tluin any meta- 
podials in the collection which pertain to the larger species of Hyrachyus. In 
Hyrachyus, metatarsal III is considerably larger than the lateral metaiKKlials. 
and this character distinguishes it from that of Palceosyops while it agives with that 
of Limnohyops. A long metatarsal III, which probably belongs to a large sixjcies of 
Hyrachytis, has its shaft much smaller and straighter than in L. laticeps-, it.s distal 
articular surface is also much less, so we may believe that the larger 8iK‘cie8 of 
Hyrachytis approached L. laticeps very closely in height but that the extriunities 
were more slender. Other remains in tlie collection pertaining to a large sjH'cies of 
Hyrachyus support this view^ The proximal portion of the secoml metatarsal has 
nearly the same form as in Hyrachytis. Its external liorder slopes gnulually tlown- 
ward, and was not so abruptly cut oil’ as in P. minor. It agrees witli that of 
Hyrachyus in having a facet for the entocuneiform. In the species of Pahrosyops 
examined the second metatarsal shows no entocuneiform facet. The suiH-rior facets 
of this metatarsal are elongated and concave. The facets on metatarsal 11 I'or the 
ectocuueiform are round and widely separated, and the anterior facet is sup]M)rte<l 
upon a constricted neck. The shaft of metatarsal 11 is slender and lamt inward, 
its anterior surface being rounded, with a tlattened posterioi portion: its distal 
articular sinTace is slender with a keel which is not prominent. Metatarsal 111 is 
the most characteristic nietapodial of this region and its articulation with the 
fourth is c[uite diffei’ent in character from that ohserved in allieil 8|K*cies. I he 
articulations between metatai’sals III and IV in Hyrachyus and Palceosyops are nnndi 
flatter than in Limnohyops, and there is no prominent prolongati()n of the e.>:ternal 
face of these metapodials. In L. laticeps, on the contrary, the anterior external 
angle of metatarsal III forms a strongly incurved hwk-like pnx-ess; thi.s 
is bordered posteriorly by a vertical facet which is oblii|ue alx)ve and 
concave below. Upon viewing metatarsal 111 from the front the pna-ess alx»ve 
described becomes prominent, and its irregular curved border terminates alxive in 
this prominent process. The ectocuneiform facet of metatarsal 111 is more concavt*. 
and more raised toward the external side than in Hyrachyus-, its distal extivinity 
is narrow and straight. 
Metatarsal lY is more slender and elongate than the corresiM)nding Ume 
of P. minor-, its surface for the cuboid is nearly j)laue. Internally and anter- 
iorly it exhibits a long narrow facet who.se surface is strongly convex; this 
articulates with the peculiar hook-shaped process of metatarsal III. forming n 
close interlocking articulation. The distal articular surface of metatarsal I V is narn)W, 
the keel of this nietapodial being very prominent and bordered externally by a deep 
notch. A strong contrast to the allied forms is the narrowness of the distal ends of 
the metapodials of this species as compared with those of P. minor. In another |)or- 
