288 PETRIFACTIONS AND THEIR TEACHINGS. CHAP. III. 



fossa is simple, and somewhat deeper than the anterior. On 

 the whole, the aspect of this humerus more closely corresponds 

 with that of the crocodiles than with its homologue in the 

 ordinary lizards. 



Thus, after the lapse of fifteen years, two important ele- 

 ments of the skeleton of the Iguanodon contained in the 

 Maidstone fossil are for the first time determined. The 

 small size of the humerus, as compared with that of the 

 femur, seemed at first to present an insuperable objection, 

 and it occasioned Dr. Melville and others of my scientific 

 friends to hesitate ere they received my interpretation of a 

 bone which had so long proved enigmatical ; but the dif- 

 ference is not greater than obtains in many other fossil 

 saurians, 1 as well as in recent Lizards. The length of the 

 Maidstone humerus is about twenty inches ; that of the con- 

 tiguous femur, thirty-three inches ; but as the latter is flat- 

 tened and extended by compression, the difference is probably 

 not more than one-third. The Isle of Wight thigh-bone is three 

 feet long : the largest specimen I have seen is four feet eight 

 inches in length : the average length of the femur in the adult 

 may be estimated at four feet five or six inches : the humerus 

 from the Isle of Wight is, therefore, not relatively longer 

 than that in the Maidstone Iguanodon. 



I have lately seen a fine distal extremity of a humerus of 

 the Iguanodon, that was collected from the cliffs at Hastings 

 by S. H. Beckles, Esq., and I have obtained a caudyloid 

 extremity of a humerus one third larger than the specimen of 

 which a cast is placed in Case G. 



METACARPALS, PHALANGE ALS, AND UNGUALS. Wall-case C, 

 right-hand shelf in lowest compartment I have sought in 

 vain for some certain indication of the bones of the fore-arm ; 



1 " C'est un fait & peu pres ge"ne"ral que les membres anterieurs des 

 reptiles crocodiliens et lacertiens sont plus courts et plus faibles que les 

 posterieurs ; chez quelques especes la difference est treVprononcee. Mais 

 nos reptiles fossiles des environs de Caen annoncent une disproportion 

 beaucoup plus forte encore entre ces membres: le Poekilopleuron, le 

 Steneosaurus de Quilly, les Teleosaurus, en fournissent la preuve. Ces 

 derniers surtout avaient les membres anterieurs d'une excessive petitesse ; 

 les deux paires de membres difteraient entre elles plus peut-6tre qu'elles 

 ne different les Gerbilles et les Kangaroos." DESLONGCHAMPS, Memoir e 

 sur le Pcekilopleuron Bucklandii^. 81. 



