98 REPTILES ALLIED TO HADROSAURUS. 
Jersey, presented by Dr. J. H. Slack. It is nearly perfect, except that the lower 
end is mutilated. When first examined and compared with the corresponding bone 
of Hadrosaurus the differences which were observable, though not very remarkable, 
led me to suspect that it belonged to Mosasaurus. ‘The fossils previously described 
as most probably representing the humerus of the latter would, of course, preclude 
such an idea. 
The specimen is rather smaller than the humerus of Hadrosaurus, and bears a 
near resemblance to it, without, however, being identical in form. ‘The two bones 
are represented in the Figs. 1-3, Plates XIV, X VII, an inspection of which serves 
to exhibit the differences better than they can be described. ‘The main differences 
are briefly as follows: The specimen in question is shorter in relation with the 
breadth, especially of its upper part; the expansion of its upper outer part extends 
more inferiorly in relation with the length of the bone, and terminates more 
abruptly than in Hadrosaurus. ‘The expansion just mentioned, viewed sideways in 
the latter (Fig. 3, Plate XIV), presents a single curved line from the summit of 
the external tuberosity; in the humerus under comparison the same line (Fig. 3, 
Plate X VII) is sigmoid, and ends below in a rough tubercle not existing in Hadro- 
saurus. The lower part of the expansion is also thicker and rougher than in the 
latter; and behind it is much more projecting, so that the surface of the shaft in this 
position is transversely concave, whereas in Hadrosaurus in the same direction it is 
convex. Independently of these differences, the Monmouth County humerus closely 
resembles that of Hadrosaurus. Its measurements, in comparison with those corre- 
sponding in the latter, are as follows :— 
MonmoutH County HADROSAURUS 
HoMEgvs. HouMeErovs. 
Inches. Lines. Inches. Lines. 
Length, : : é estimated, under 21 22 6 
Breadth at the Pveroaitics : : : about 6 9 6 10 
Thickness at head . 3 6 3 3 
Breadth of shaft just above maiciale) 5 6 5 4 
Thickness in same position 2 5 2 4 
Breadth of lower portion of This 2 10 3 2 
Thickness of lower portion of shaft 2 9 2 9 
Circumference of lower portion of shaft . 9 2 9 6 
Breadth at condyles, . ; estimated, under 5 5 
Diameter of head . 2 4 2 
6 
Several fragments, apparently of both femora, of a huge animal, from the Marl, 
near Swedesboro, Gloucester County, New Jersey, were presented to the Academy 
by David Ogden. The more characteristic of these nearly corresponds in form with 
that portion of the femur of Hadrosawrus between the distal extremity and the 
process of the middle part of the shaft. If it really appertained to the Saurian 
just named, the breadth and thickness of the fragment, in relation with the length 
of the Hadrosaurus femur above described, would indicate: the bone in its perfect 
condition to have been nearly five feet in length. The fragment in its present state 
is seventeen inches long. The lower end is composed of coarse, spongy substance, 
indicating its proximity to the articular extremity. The upper end is much less 
quadrate than the femur of Hadrosaurus would appear to be in a corresponding 
