9 
4871. ] 281 [Cope. 
fore limb ; the pelvic arch complete with one hind limb complete to tar- 
sus, with phalanges. The premaxillary is wanting, but the adjacent 
suture of the maxillary remains. 
The fronto-nasal septum is convex in transverse section. The mazil- 
lary bone is much attenuated anteriorly, and supports thirteen teeth. 
The ramus mandibult is high and slender; the angle is quite produced, 
and the median articulation indicates considerable mobility. The pala- 
tine bones are narrower than in any of the species previously described. 
They are deeply notched for union with the pterygoids, and the superior 
posterior process terminates inan acute cone. In front of the articulation, 
the bone is a vertical plate slightly concave on the inner side ; the ante- 
rior half is subquadrate in section, the outer face subvertical, the inner, 
regularly rounded. The inferior surface is marked with a groove which 
passes from the inner side to the outer. The portion on the outer side of 
this groove, is on the distal third of the bone produced downwards into a 
prominent keel or ridge. The anterior extremity is an acute point. Each 
bone bears eleven teeth, all of which have the external faces of their roots 
exposed. The bones are curved outwardly from the fourth tooth from 
behind ; opposite the sixth there is longitudinal concavity on the inner 
face. 
The occipital region and suspensoria are not present, but both, quadrates 
were found perfectly preserved excepting the thin ala. They present 
marked characters, being most nearly allied to those of L. proriger and L. 
validus. The proximal articular surface exhibits an obliquity in the 
transverse direction. It presents a large external angle which instead of 
being nearly at right angles to the axis of the main portion of the surface, 
is nearly in the same line. The decurved posterior hook is very short. 
The distal articular surface has, like that of other Liodons, a small trans- 
verse extent, and is divided by a concavity into two tuberosities. The 
outer of these receives at its angle the prominent narrow portion of the 
external ridge, which extends from the external proximal angle. The 
prominence of this ridge is greater than in any other species except Z 
proriger ; it is acute throughout its length and has a gentle sigmoid flex- 
ure. The basis of the great ala includes a smaller area than usual and is 
continuous with a prominent narrow ridge which proceeds from inside the 
metal crest. The metal crest takes the place of the “knob” in such 
Mesasauri as M. dekayi, it projects strongly backwards and outwards as 
an angle of two ridges ; the inferior being acute and curved and termina- 
ting above the middle of the distal condyles. The meatal pit is not con- 
cealed between ridges, but is external ; its form is peculiar, being a nar- 
row oval, three times as long as wide, directed downwards and forwards. 
Thus the characters of this element are well marked among those per- 
taining to the other species. 
The teeth are not much compressed, and have a cutting angle on the an- 
terior and posterior margins, which separate nearly equal faces. 
The vertebral centra change in form from the anterior to the posterior 
A. P. §.—VOL. XII—2J. 
