112 BRITISH POSSIL REPTILES. 



the fore part is produced into a strong ridge, here partly broken away. The distal 

 end is 5 inches across, and is moderately concave transversely behind. An osseous 

 tubercle, 1 inch 4 four lines by 10 lines, is cemented to the anconal surface ; a 

 second similar bone is attached to the interspace 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 (PI. 50, 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 (PI. 49, 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 6 inches, with a thickness of the shaft not 

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

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

 respect resembUng the same bone in the Dicynodonts.^ 



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

 lencfth of the humerus, would be those of the same limb in Teleosaurus. The 

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

 lated middle dorsal vertebrte. There is no trace of clavicle in the present speci- 

 men ; the functions of the fore limb seem, therefore, to be 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, 18-58,' show the distinction from the Croco- 

 dilian order and the afl&nity to the Thecodontion 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. 



1 Op. cit., vol. i, p. 31, vol. ii, pis. 30—36. 



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

 Elgin matrix of Stagonolepis, it waa stated that " no characteristic Devonian or Old Eed 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 mesozoic period." 



