50 



FOSSIL REPTILIA OF THE 



Ah outline of a section of this part is given at Fig 1. It presents the same can- 

 cellous structure as the tibia, but the 

 concentric arrangement of the layers 

 of cells is more exact. Towards the op- 

 posite end of the bone the concave side 

 becomes first flat, and is then produced 

 into a convex wall, terminating one end 

 of a transverse section of a compressed 

 and bent thick plate of bone. The long 

 diameter of this section is 6 inches 6 lines 

 at the end of the fragment ; 4 inches from 

 that end it measures 5 inches 6 lines : 

 the shorter diameter of the compressed 

 bone at the same part is 1 inch 10 lines ; 

 an outline of the transverse section of this 

 part is given in Fig. 2. Of several long 

 and strong bones, which from their form and relative size 

 represent metatarsals, there are considei'able portions 

 of four, detached, with their proximal articular surfaces 

 preserved; a fifth, wanting the articular extremities; 

 and two others longitudinally split and imbedded in a 

 mass of the Green-sand matrix ; these latter exhibit the 

 characteristic inecmality of length of the Crocodilian 

 metatarsals, and are probably the innermost and second 

 metatarsals of our present gigantic Saurian. 



The innermost and smallest measures one foot in 

 length ; the adjoining metatarsal two feet. Their position 

 in the rock shows that the part of the skeleton had been 

 separated through decomposition before they were per- 

 manently imbedded, the proximal articular extremities 

 being 3 inches apart, but on the same transverse line. 

 The outline of the larger of these imbedded meta- 

 tarsals is subjoined at fig. 3 ; its transverse diameter at 

 a, is 8 inches, at b, 4 inches 5 lines, and at c, 6 inches. 

 The smaller metatarsal is more contracted at the 

 shaft which presents a triedral contour : the diameter 

 of its greater end is 5 inches ; that of the narrow part 

 of the shaft is 1 inch 1 1 lines ; its compact outer crust 

 is between one and two lines thick ; all the rest of the 

 substance presents a cellular texture, the cells having 



Outline of an imbedded metatarsal of the Poly£&- a diameter of One half to tWO thirds of a line. 



chodon. Scale ~% inches to a root. 





