Jrom the Greensand of New Jersey. 393 
This species appears to be readily distinguished from those 
already known, with the exception, perhaps, of Mosasawrus max- 
wus of Cope, which has not yet been fully described. So far 
as it has been defined, however, it presents marked differences 
from the present species, particularly in the quadrate bone, one 
of the most characteristic portions of the skeleton. In IM. prin- 
ceps, the proximal end of the quadrate forms an open sigmoid, 
the process at the angle over the great ala is much smaller than 
that of the external angle, and the knob just within the meatus 
of the ear is ve rominent. There is also a large foramen 
near the medial line, a little below the center, which is not given 
Prof. Cope’s figure of the quadrate of M. maximus.* The left. 
quadrate of the present specimen is eight inches in length, four 
and two-thirds inches in breadth from the outer side of the pit 
near the meatus to the edge of the great ala, and five inches 
across the articular face of the distal extremity. 
rst onmouth 
, New Jersey, during the excavation of a ditch by the well 
known Cream Ridge Marl Company, and, with most of the speci- 
liberality in preserving such valuable specimens, and render- 
Ing them available for investigation. 
Mosasaurus Copeanus Marsh, sp. nov. _ : 
The remains which at present represent this species are por- 
tions of a skull with some of the maxillary teeth, and part of 
the corresponding lower jaws, including the anterior extremity 
of the left ramus, and the articular surface of the left splenial 
bone. They indicate one of the smallest Mosasauroids yet dis- 
covered, and one very distinct from any hitherto known. The 
teeth are slender, compressed, considerably curved, and deeply 
facetted. They are very pointed, and a sharp ridge, without 
denticulations, divides the outer from the inner surfaces. The 
enamel of the crown is remarkably smooth, and quite unlike 
the usual corrugated dental surfaces of the larger Mosasauroids. 
The dimensions of a very perfect tooth from near the middle of 
the left lower jaw are as follows — 
* Transactions of Am. Philosophical Soc., vol. xiv, pl. x1, fig. 7, 1869. 
4 
