1871.] 43 {Cope. 
and presents less powerful development of the interior ridge for the 
pterygoid muscle. The cotylus descends abruptly behind it. The coro- 
noid bone exhibits the usual anterior fissure. ‘The rolled front margin of 
the ascending portion is thickened. The superior surface of the anterior 
part of the frontal bone, is lumpy and with some shallow pits ; the outer 
face of the articular is smooth. The vertebra preserved is a posterior 
lumbar, and is injured; the anterior articular face is nearly round. Its 
vertical diameter is M.058. Length of centrum M.008. 
The forms of the teeth distinguish the Liodon sectorius from the species 
of Mosasaurus, and that of the vertebra, from such species as Liodon 
perlatus, Cope, and L. dyspelor, Cope. There remain to compare with it, 
L. proviger, Cope; L. mitchillii, Dekay ; L. laevis, Owen; L. congrops, 
Cope; L. tetericus, Cope; and L. mudgei, Cope. In size it will only 
compare with the first two species, being from twice to four times as 
large as any of the remaining four. The flattened teeth distinguish it a 
once from JL. éetericus, and the abrupt rising superior margin of the 
articular bone, from the L. mudget, where the upper and lower margins 
are for some distance parallel. The less compressed vertebral centrum 
distinguishes it from ZL. laevis. From the two large species, dental 
characters separate it. Thus in L. proriger the teeth are less compressed, 
and are facetted, especially the anterior ones, with concave grooves sep- 
arated by obtuse ribs. In IM. mitehillit the teeth present more similarity, 
but are abundantly distinct. They are much less compressed, even where 
the posterior cutting edge is strongly developed, the external face is con- 
vex to the apex and without concave or flat facet ; it is narrower at the 
base as compared with the height, and has an incurvature not seen in this 
Liodon. The enamel is smooth, and not striate under the glass. 
This and the L. miichillé ave the largest Liodons of the Eastern cre- 
taceous. I have recently obtained three anterior dorsal vertebrae and a 
tooth of the latter, from the lower bed of cretaceous green sand near 
Freehold, N. J. The vertebrie rival in size those of Mosasaurus dekayt, 
but are of a more elongate form. The articular extremities are cordiform 
oe 
and nearly round, the posterior with the smooth neck band just in front 
ofits margin. In front of this, the surface is sharply striate, especially 
on the inferior aspect ; the same appears on the bases of the diapophysis. 
The tooth is like one of those described by Leidy. (Cret. Rept. Pl. XI.) 
* The Léodon sectorius was obtained by Judson C. Gaskill, from the marl 
pits of the Pemberton Marl Co., at Birmingham, N. J., and liberally 
placed at my disposal by him. 
ADOCID A. 
The species of this family display considerable differences in the nature 
of the sutures of the bones of the plastron. In the thickest species the 
sutures are fine and the processes very small. This is especially the case 
with Adocus pectoralis. In .A. beatus which is thinner, the sutures are 
coarser, but without gomphosis ; that between the hyo- and hyposternal 
elements looking as though a slight mobility existed in life, as I have 
