The arm-bone (humerus) of the Iguanodon has been discovered in the Wealden of the Isle of Wight by Mr. Fowlstone; it is figured and described in Petrif. p. 286. The humerus is also present in the Maidstone specimen[649] of Iguanodon, before referred to at page 692: in pl. ii. of Wond. this bone is termed the radius. The humerus of this reptile is much smaller than the femur; in the Maidstone specimen the former is about 20 inches, and the latter about 33 inches in length.
[649] The two bones marked "6" in pl. ii. Wond. and in Lign. 65, Petrif. (one of which is figured in outline in [Lign. 226], fig. 4,) regarded by Prof. Owen as the radius and ulna (the two bones of the fore-arm): the author’s reasons for regarding these bones as metacarpals are given in full at p. 289, Petrif.
As separate bones of the feet of the Iguanodon, for example, metacarpals, metatarsals, phalangeals, and unguals, often occur in the strata of the Wealden, figures of several specimens, on a reduced scale, are introduced in [Lign. 226], and may enable the student to identify those he may meet with in his researches.[650] The ungual phalanges, or claw-bones, which were invested with the nail, are sometimes found of an enormous size; from a quarry near Horsham, Mr. Holmes obtained specimens more than five inches long, and three inches wide at the articular extremity.
[650] See Rep. Brit. Assoc. 1841, pp. 137-142.
Length of the Iguanodon.—The length of the united head and trunk, according to my estimate in Geol. S. E. p. 316, is seventeen feet and a half; by Professor Owen’s estimate it is reduced to fifteen feet;[651] a difference of no importance in such merely approximative calculations, particularly when the form of the cranium is unknown.[652]
[651] Ibid. p. 144.
[652] The more recently discovered specimen of lower-jaw, already referred to, page 693, indicates a length of between three and four feet for the entire jaw, Petrif. p. 249.
Lign. 226. Bones of the Feet and Claws of the Iguanodon.
Wealden. Tilgate Forest.
(See Wond. pl. in.)