REPTILES ALLIED TO H A D R S A U R U S. IQl 



short distance of the articular ends without being narrowed by an accumulation of 

 spongy substance. 



The measurements of the specimen are as follows : — 



Lines. Inches. 



Extreme length ••........ 15 6 



Greater diameter at middle of shaft ....... 1 4 



Smaller diameter at middle of shaft 1 



Breadth of head 3 4 



Thickness of head 2 1 



Breadth of tarsal extremity ........ 2 7 



Thickness at inner anterior border of tarsal estremity ... 1 4 



The other specimens referred to consist of several fragments of a tibia, portions 

 of two metatarsals, and three phalanges, from a much larger individual, if not a 

 different species, indicated by the tibia just described. The specimens are from 

 Monmouth County, and were submitted to my inspection by O. R. Willis, of Free- 

 hold, through Prof. Cook. 



The tibial fragments consist of the greater portion of the upper articular 

 extremity (Fig. 6, Plate XVII), and the lower one (Fig. 7) preserved entire. 

 Both have the same form as the corresponding portions of the tibia above described, 

 but are much larger. Thus the thickness of the head is three inches ; the breadth 

 of the tarsal extremity is nearly four inches ; and the thickness at the inner ante- 

 rior border of the latter one inch and three-quarters. The medullary cavity is very 

 capacious, being intermediate in this respect to the condition observed in ordinary 

 mammals and birds. It reaches to within a short distance of the articular surfaces 

 of the ends of the bone without being narrowed through the accumulation of can- 

 cellated substance. 



One of the fragments of a metatarsal is represented in Fig. 8, Plate XVII. It 

 is the distal end ; has a quadrate shaft and a single articular head. The impres- 

 sions for the attachment of lateral ligaments are remarkable for their depth. The 

 interior of the fragment exhibits a medullary cavity corresponding in its capacity 

 with that of the tibia. 



The three phalanges (Figs. 9-11, Plate XVII) are aU from the first series, and 

 resemble the corresponding bones of Crocodiles ; two are alike ; the third is longer 

 and narrower than the others. The proximal extremity, which is the broader, 

 presents a single articular concavity. The distal extremity presents the common 

 hour-glass-like or trochlear articular surface, and, as in the case of the metacarpal 

 fragment just described, is depressed at the sides into deep pits, corresponding with 

 the usual attachments of lateral ligaments. 



The measurements of the shorter phalanges are as follows : — 



Inches. Lines. 



Length laterally 3 5 



Breadth of proximal end 2 



Depth of proximal end ......... 1 Y 



Breadth of distal end ........ 1 6 



Depth of distal end laterally -1 1 



