112 FOSSIL REPTILIA OF THE 



straight clavicle of the Iguana, Amblp-hi/nchus, and some other lizards, justifies the. 

 expectation of some unexampled modifications of that variable bone in a great extinct 

 reptile of a different order. 



For a knowledge of the bone, called " scapula" and " humerus," in T. XXXIV, I 

 am indebted to Mr. George B. Holmes, of Horsham, who, in March, 1847, transmitted 

 to me a beautiful drawing of both bones, together with the coracoid in natural juxta- 

 position with the humerus, discovered " in one block of stone, with other bones of the 

 same individual" in Tower Hill Pit, near Horsham. That gentleman, whose collection 

 of the Wealden Fossils in his neighbourhood is one of the most instructive extant, had 

 correctly determined their nature, and named them in the drawing which he sent 

 to me " Humerus, Scapula, and Coracoid bone of the Iguanodon." 



Dr. Mantell published similar determinations of homologous bones, in the ' Philo- 

 sophical Transactions' for 1849. This part of the skeleton of Iguanodon may, therefore, 

 be regarded as definitely restored. 



The scapula in the Maidstone specimen, T. XXXIII, lies broken across the femur: 

 it is a long, narrow, flattened bone gradually expanding to its free end, more suddenly 

 towards its articular end ; but this is too much mutilated to give its true character in 

 the specimen in question : it will be described from Mr. Holmes's beautiful specimen 

 in the ' Monograph of the Fossil Reptiles of the Wealden.' 



The humerus (see T. XXXIV) is shorter than the scapula, and much shorter than 

 the femur, its relative proportions to which are the same in the Iguanodon, as in the 

 Teleosaurus (see T. XI, Monograph on the Crocodilia of the London Clay), and, with 

 the vertically developed tail of the Iguanodon indicate the aquatic habits of that 

 gigantic reptile. The head of the humerus is hemispheroid, and projects between two 

 sub-equal tuberosities ; a deltoid ridge is continued nearly half way down the bone 

 from the outer tuberosity, and, where it subsides, the shaft is bent a little inwards, 

 contracts, and then again expands to the distal condyles, which are rounded and pro- 

 minent, with a moderately deep depression between them at the back, which is the 

 part of the bone exposed in the Maidstone specimen. 



The radius and ulna lie with their proximal ends next the right hand upper corner 

 of the slab of the Maidstone specimen ; the latter being distinguished by its prominent 

 olecranon, which is rounded as in the great Monitor (Varanus niloticus). I shall reserve 

 the description of the metacarpal and metatarsal bones for a succeeding Monograph, and 

 shall only observe, here, that the claw-bones marked "ungual phalanx" in T. XXXIV, 

 though varying in their proportions in the two specimens preserved, are broader, more 

 depressed, and less incurved than those of other known Saurians. 



The ilium which lies detached near the lower border of the slab in the Maidstone 

 specimen, is the left one, with its sacral articular surface or inner surface uppermost, 

 the extent of which plainly indicates the great length of the sacrum in the Iguanodon, 

 as compared with existing Lizards, since it equals the anteroposterior diameter of five 



