LOWER LIAS. 3 



The transverse section of the middle of the shaft is nearly circular ; the 

 thickness of the compact wall of the medullary cavity is here about one sixth of the 

 transverse diameter of the bone. I have not seen a bone of any other 

 Dinosaur indicative of more vigorous action of the hind limbs than the present 

 femoral shaft. 



The foregoing interesting and instructive fossil was accompanied by the shaft 

 of a tibia of corresponding size, crushed and broken at both ends; it measured 

 18 inches in length and 2 inches 8 lines in diameter at its middle, the circum- 

 ference of the shaft there being 10 inches. 



These proportions indicate a hind leg, longer and more slender, relatively to 

 the trunk, than in the Megalosaur, Iguanodon, or other Dinosaur with which 

 such comparison may be made. The bone being fractured across the middle of 

 the shaft, shows a large medullary cavity ; the compact, bony wall does not 

 exceed 3 lines in thickness, the cavity itself being ] inch 3 lines in diameter. 



At the proximal end the antero-posterior expansion and its ridges have been 

 broken away. The bone gradually contracts, as it descends, to a subtriedral shaft, 

 with a triangular transverse section, two of the angles being rounded off, and 

 the third remaining, which was opposite the fibula. The distal expansion has 

 been, in like manner, broken away ; but its commencement shows the rise of an 

 anterior ridge in addition to the fibular one. I did not think it necessary to 

 figure this fossil, as I shortly after received from Mr. Harrison and Mr. Henry 

 Morris, F.R.C.S., of Charmouth, the subjects of the two following plates. 



Parts of the Femur, Tibia, and Fibula forming the Knee-joint. Tab. II. 



in the specimen figured from three views (figs. 1, 2 and 3) in this plate, the 

 lower half of the right femur and the upper halt of the right tibia and fibula are 

 cemented by the matrix in the natural relative position in which they enter into 

 the formation of the knee-joint, when bent. This remarkable specimen indicates 

 the tranquil state of the sea-bed or bottom after it had received the dead 

 carcass of the Dinosaur. No agitation or other external violence has displaced 

 the bones of the leg after the solution of the ligaments which tied them 

 together in the living animal; when the depth to which they had sunk, and 

 the consistency of the mud or clay bed, tended to retain them in their natural 

 position. The portion of femur preserved indicates a slight backward bend of 

 the shaft, which at the fractured part — probably a little below the middle of 

 the bone — presents an almost circular transverse section. The circumference 

 here is 10 inches ; the compact wall of the bone is 6 lines thick ; the medullary 

 cavity 2 inches in diameter. A little below the fractured end, and 8 inches above 



