308 BRITISH FOSSIL REPTILES. 



eating a total length of 3 feet. In a Memoir, communicated by Dr. Mantel! to the Royal 

 Society, and printed in the 'Philosophical Transactions' of 1841, the author dissents 

 from the opinion of Cuvier ; remarking, that, " In none of the skeletons of reptiles, 

 or, indeed, any other animals to which he had access, are there any bones with which 

 these fossils could be identified."* He regarded, therefore, the term clavicle as being 

 manifestly inappropriate and liable to lead to misconception ,and proposed to distinguish 

 the bone in question by the term " os Cuvieri, as the Cuvierian element of the pectoral 

 arch of the Iguanodon."t From a reference to myself, in the same page, it might be sup- 

 posed thatlhad concurred in this view of the introduction of a new element in the scapular 

 arch of the Iguanodon ; but at the time when I assisted Dr. Mantell in the comparison of 

 the bone in question, I was not aware that he entertained any such view of it as was 

 afterwards expressed in the Royal Society's Transactions. " In a very small lizard in the 

 Hunterian Museum, Mr. Owen pointed out to me a bone attached to the coracoid and 

 omoplate, that bore some analogy to the bone in question.'' The clavicle of the lizard 

 alluded to {Cydodus nigroluteus), bore sufficient resemblance, as I have before stated 

 (Section II,' Cretaceous Reptiles, 'p. 265), to the long and slender fossil under comparison, 

 to confirm the conjecture of Cuvier ; but it lent no support to the idea of the long and 

 slender fossil in question being a peculiar superaddition to the Saurian skeleton. The 

 bone is compressed, slender, and sub-trihedral at the middle part, expanded and 

 flattened at the two extremities, bent with a slight double curve in a graceful sigmoid 

 form. The broadest end, which, from the analogy of the Cyclodus lizard, must be 

 regarded as the median or pectoral extremity, gives off two processes, the first 

 appearing as a continuation of the thinner margin of the bone, twisted and produced 

 obliquely downwards ; the second process is given off nearer the expanded sternal end, 

 towards which it slightly curves. 



The breadth of the expanded sternal end of a clavicle, 29 inches iu length, is 

 The breadth of the scapular end ..... 

 From this extremity to the base of the first process 

 The breadth of the narrowest part of the shaft . , 



In the clavicles preserved in the Maidstone Iguanodon, the short pointed process is 

 sent off at the angle where the shaft slightly bends as it expands into the sternal 

 extremity ; and the second process is a broad subquadrate flattened ])late. In the 

 Cyclodus lizard the clavicle is bent at an open angle, but nearer the middle of the 

 shaft than in the Iguanodon ; the known differences of form presented by the clavicles 

 in the genera Cydodm, Idiurus, Grammatophora, Jjiibh/rJ/i/iidus, and Tfjuana, would 

 have justified the expectation of some unexampled modifications of that variable bone 

 in a great extinct Reptile belonging to a different order of the class. 



* 'Phil. Trans..' pt. ii, 1S41, p. 138. t I^id. 



