14 FOSSIL REPTILIA OF THE 



space between the inner condyle and the slightly dislocated ulna. These are more 

 probably parts of the scattered dermo-skeleton than tendinal sesamoids of the 

 extensor of the forearm 



The acromial end of the ulna (Tab. Ill, 55) presents a convex border 2 inches 

 2 lines in breadth. The mutilated head of the radius (ib., 54), preserving its natural 

 relations to the outer condyle of the humerus, is 1 inch 6 lines in length. 



The shafts of the radius and ulna, with the rest of the bones of the fore limb, 

 have been broken away. 



Four oval, dermal bones, like those overlying the humerus and ulna, are attached 

 to the matrix in front of the humerus and radius. 



Behind the fractured sternal end of the right coracoid (Tab. II, 52) is the dislo- 

 cated head (53) and anterior expanded pectoral process {p ) of the right humerus 

 (ib.), showing a thickness of 7 lines where it has been broken off. The transverse 

 diameter of the humerus at this part is G inches, with a thickness of the shaft not 

 exceeding 2 inches 9 lines, showing that the humerus in Scelidosaurus was more 

 expanded and compressed proximally than in any existing reptile, and in this 

 respect resembling the same bone in the Dicynodonts. 



The proportions of the entire fore limb of Scelidosaurus, as indicated by the 

 length of the humerus, would be those of the same limb in Tdeosaurus. The 

 humerus is shorter than the scapula, barely equalling the extent of four coarticu- 

 lated middle dorsal vertebrae. There is no trace of clavicle in the present specimen ; 

 the functions of the fore limb seem, therefore, to have been less important in regard 

 to locomotion on land than in Iguanodon, Megalosaurus, and modern Lizards. Yet 

 the shape and proportions of the coracoid, as I pointed out in regard to the 

 Stagonolepis when the remains and impressions of that reptile were submitted to 

 my inspection by Sir Roderic I. Murchison, at Leeds, during the meeting of the 

 British Association, September 24th, 1858,* show the distinction from the Croco- 

 dilian order and the affinity to the Thecodontian order and to modern Lacertilia, 

 or give evidence of a more generalised reptilian character, in these extinct reptiles 

 with dermal bones and scutes of the Lower Liassic and Upper Triassic deposits. 



Pelvic Arch and Limb. Tabs. VI, X, XI. 



The left iliac bone (Tab. VI, figs. 1 and 2, 62) retains almost its natural 

 relations with the sacrum. The right iliac bone (ib., 62) has been obliquely 

 dislocated. It is a long bone, with a sigmoid flexure (ib., fig. 2, 62), convex 



* Art. "Palaeontology," 'Encyclopaedia Britannica,' vol. xvii, p. 130, in which, in reference to the 

 Elgin matrix of Star/onolepis, it was stated that " no characteristic Devonian or Old Red fossils of any 

 class have been discovered associated with the foregoing evidences of reptiles, which, according to the 

 determination of strata by characteristic fossils, would belong to the secondary or mezozoic period." 



