806 



Pectoral arch. — A perfect scapula discovered in the strata of Til- 

 gate Forest, and which corresponds with the coracoid bone, provi- 

 sionally assigned to the Iguanodon in the memoir of 184-1 (Phil. 

 Trans. PI. IX. fig. 11), Dr. Mantell has been enabled to refer to that 

 reptile, by the fortunate interpretation of portions of two scapulae 

 which are preserved in the Maidstone specimen, but had not pre- 

 viously been recognized as such. As the clavicles were long since 

 determined, the essential elements of the pectoral arch are now as- 

 certained, and the author gives a restored outline of this important 

 part of the skeleton, based upon these data. 



Humerus. — A humerus three feet long, discovered by Mr. Fowles- 

 tone in the Isle of Wight, has been ascertained by the author to belong 

 to the Iguanodon, from the presence of a small but corresponding 

 bone in the Maidstone fossil. This bone, from its disproportionate 

 size in comparison with the femur with which it is collocated — being 

 one-third shorter — was formerly assigned by Dr. Mantell to the fore- 

 arm ; but the large humerus from the Isle of Wight, which, except 

 in magnitude, is identical with that from Maidstone, leaves no doubt 

 upon the subject. It is now therefore, for the first time, ascertained, 

 that in the Iguanodon, as in many fossil and recent reptiles, the an- 

 terior extremities were much shorter and less bulky than the poste- 

 rior. The radius and ulna are still undetermined, but the author 

 states that there are some imperfect bones in his former collection, 

 now in the British Museum, v/hich he thinks will be found to belong 

 to the fore-arm. 



Hinder extremities. — The colossal magnitude of the Iguanodon is 

 strikingly shown by some femora- and leg-bones recently discovered. 

 One femur is 27 inches in circumference, and must have been 4 feet 

 8 or 10 inches in length ; and a tibia, found with the same, is 

 4 feet long. 



Dermal scutes and spines. — The author figures and describes se- 

 veral dermal scutes and spines, and states that a microscopical exa- 

 mination of the large angular bones of the Hylaeosaurus (Phil. Trans. 

 184-1, PL X. fig. 1), supposed by him to be ossified dermal spines, 

 but which Professor Owen regarded as the abdominal extremities of 

 ribs, proves the correctness of his own opinion ; their structure being 

 identical with that of the acknowledged dermal scutes. 



In the summary which concludes the memoir. Dr. Mantell states 

 that the facts described confirm in every important point the phy- 

 siological inferences relating to the structure and habits of the Igua- 

 nodon and Hylseosaurus, enunciated in his former communications; 

 and thus, after the lapse of a quarter of a century, he concludes his 

 attempts to restore the skeletons of the colossal saurian herbivores, 

 of whose former existence a few water-worn teeth and fragments of 

 bones were the only indications, when, in 1825, he first had the ho- 

 nour to submit to the Royal Society a notice on the teeth of the 

 Iguanodon. 



