98 REPTILES ALLIED TO IIADROSAURUS. 



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 HadrosauTus 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, XVII, 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 iuferiorly 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 XVII) 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 difterences, the Monmouth County humerus closely 

 resembles that of Hadrosaurus. Its measurements, in comparison with those corre- 

 sponding in the latter, are as follows : — 



MosMOnTH CODNTY Hadrosaueus 



Hdjierds. HnMERns. 



Inches. Lines. Inches. Lines. 



Length, .... estimated, under 21 22 6 



Breadth at the tuberosities . . . about 9 6 10 



Thickness at head ........3 6 3 3 



Breadth of shaft just above middle ... 5 6 54 



Thickness in same position ..... 2 5 24 



Breadth of lower portion of shaft .... 2 10 3 2 



Thickness of lower portion of shaft ... 2 9 29 



Circumference of lower portion of shaft ... 9 2 96 



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 Hadrosatirus 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 



