100 REPTILES ALLIED TO HADROSAURUS. 



of its shaft at the middle is three inches and three-quarters; its thickness two 

 inches and a half. 



Dr. Slack presented to the Academy four fossil bones, from the Green-sand of 

 IMonmouth County, New Jersey, which at first puzzled me as to their position 

 in the skeleton. They bear a resemblance to the bodies of the sacral vertebrae of 

 the Iguauodon, from which I suspect them to be the corresponding bones of a young 

 Iladrosaurus. The specimens are aU mutilated, and the best one is represented in 

 Figs. 27, 28, Plate XIII, as a representative of the whole. Three of them are 

 four inches and a half in length, the remaining one four inches. They are much 

 constricted at the middle and rapidly expand towards the extremities, Avhich termi- 

 nate m slightly depressed or nearly plane, rough, cordiform articular surfaces. The 

 lower part of the body forms a thick, transversely convex, carina-like ridge, deeply 

 concave from before backward. The upper angles are bevelled off for conjunction 

 with the sacral ribs or pleurapophyses, between which on each side is a wide notch, 

 part of the foramen for the transmission of the sacral nerves. The sacral canal 

 forms a deep groove, concave antero-posteriorly and transversely. Supposing that 

 Iladrosaurus had six vertebree to the sacrum, as in Iguanodon, the length of this 

 bone in the young individual to which the specimens belonged would have measured 

 about twenty-six inches in length. 



Since ^vriting the foregoing. Prof Cook, of New Brunswick, New Jersey, has sent 

 to me for examination a collection of fossUs, from Monmouth Comity, New Jersey. 

 Among them are several uncharacteristic fragments of bones of the extremities and 

 portion of a vertebral body of some huge animal which I suspect to be Iladrosaurus. 

 The specimens were obtained from the farm of the Rev. G. C. Schenk, of Marlboro, 

 Monmouth County. 



The collection also contains portion of the shaft of a femur, obtained by Dr. 

 Conover Thompson, from Freehold, Monmouth County, probably belonging to a 

 young Iladrosaurus. The specimen corresponds in form and construction with the 

 middle part of the shaft of the femur of the Haddonfield Iladrosaurus, but is much 

 smaller. It is four sided, hoUow interiorly, and exhibits the remains of the con- 

 spicuous process postero-internally. The shaft about the middle of the process 

 measures three inches and three-quarters in diameter transversely, and a little over 

 three inches antero-posteriorly. 



A few remains have come under my observation, from the Green-sand formation 

 of New Jersey, which indicate one, or perhaps two, comparatively small species of 

 terrestrial or amphibious Sauria, apparently allied to Iladrosaurus. 



One of the specimens, contained in the cabinet of the Academy, consists of an entire 

 tibia, from Burlington County, and is represented in Fig. 3, Plate III. It resembles 

 the tibia of Iladrosaurus, but besides being a very much smaller bone it is propor- 

 tionately very much more slender ; or, in other words, it is much longer in relation 

 with the breadth of its extremities. The shaft is trihedral, and of nearly uniform 

 diameter to within a few inches of the latter, which have nearly the same form and 

 relative position in regard to each other as in Iladrosaurus. The interior of the 

 bone is excavated with a capacious medullary cavity, which continues to within a 



