280 PETRIFACTIONS AND THEIR TEACHINGS. CHAP. III. 



Monitors is a slender, gently curved, bone, stretching from 

 the scapula to the sternum, and attached to each by a simple 

 extremity ; but in others of the lacertians the median or 

 pectoral end is more complicated, and in some respects re- 

 sembles the clavicle which I have ascribed to the Iguanodon. 



None of the isolated bones of the Iguanodon occasioned 

 me more perplexity than this element of the pectoral arch, 

 especially as a fragment of the mesial extremity was for a 

 long while the only portion obtained. Even when the perfect 

 bone in the Case before us was discovered, it was very em- 

 barrassing to determine to what part of the skeleton it 

 belonged. Baron Cuvier, to whom I sent a sketch of the 

 fossil, thought at first it was a fibula, and afterwards that it 

 might be a clavicle ; but if it were, it did not resemble that of 

 a reptile, nor, indeed, of any other living creature. Upon 

 taking it to the Hunterian Museum, Mr. Clift could discover 

 no bone at all resembling it, excepting the first rib of an 

 Ostrich, which has processes bearing a distant resemblance to 

 the apophyses observable at the pectoral extremity. 



In the "Geol. S.E. of England," this bone is figured (Plate 

 IV.) and described, with the remark that the only place in 

 the skeleton it could be referred to, was either the thorax or 

 the lower extremities : " it may be a fibula, a rib, or a clavicle ; 

 and that it is a clavicle of some extraordinary extinct reptile 

 is the most probable supposition." 



In 1841, when labouring under a severe indisposition from 

 which recovery was thought hopeless, I communicated to 

 the Royal Society a few notes on the reptilian remains I had 

 collected, with a view to assist future observers, and at the 

 same time I presented to Professor Owen the drawings of all 

 my principal specimens, which I had prepared with a view to 

 publication ; for I was anxious that the labour I had bestowed 

 upon this investigation might be made available to science. 1 

 In that Memoir, the bone in question is thus described : 

 " Several bones evidently referable to a complicated sternal 

 apparatus, and approximating to that of the Lizards, were 

 discovered many years since ; and one of these of a very 

 extraordinary form was figured and described in " Foss. Tilg. 



1 Appendix G. Drawings of remains of Fossil Keptiles from Tilgate 

 Forest. 



