446 M. W. Hooley — Iguanodon mantelli — 



foi- articulation with the ilium. The area between these extremities 

 and the obturator process is basin-shaped. The obturator process is 

 strongly developed and produced some distance from the shaft. The 

 extremity is expanded and curved. The postaxial border of the 

 wliole bone is thicker than the preaxial, which is compressed into 

 a thin edge. The sliaft is twisted so that the preaxial margin 

 becomes ventrally postaxial. The ventral extremity of the shaft is 

 expanded pre-postaxially. 



Detekm[nation of the Specimen. — These remains belonged to 

 an individual exceeding the dimensions of /. hernumrtensis, which 

 would appear to preclude their identification with /. mantelli, 

 for all the bones of the latter found either in England or at 

 Bernissart have been nearly equal in size and much smaller and more 

 graceful than those of /. bernissartensis. But the cliaracters of the 

 bones now being considered are identical witli tliose which have been 

 ascertained from tlie type fossil from Maidstone and the specimen of 

 Bernissart, and leave no doubt that they are one and the same species. 

 These characters are the presence of fi.ve vertebrae in the sacrum, the 

 form of the pre-acetabular portion of the pubis, and the position of 

 the median trochanter in the middle third of the shaft of the femur. 

 The figure of the pelvic bones and femur of /. mantelli given by 

 Professor L. Dollo ^ admirably represents the bones under review, 

 and consequently they differ from the figure (fig. 4) of the same 

 bones of /. bernissartensis given on the same plate. I was surprised 

 to find that no detailed description and measurements of the sacrum 

 and bones of the pelvis or illustration of the sacrum of either of the 

 Iguanodons of Bernissart had been published, and I recently wrote to 

 Professor L. Dollo, who informed me that he was at the present time 

 engaged on a monograph in which they would appear, and also that 

 in reality there is only one specimen tliat belongs witli certainty to 

 /. mantelli in the collection of Bernissart against more than twenty of 

 /. bernissartensis. 



Sundry measurements have been given, and before discussing the 

 questions arising from their great dimensions it will be well to 

 compare them with tliose of the present specimen. 



The length of the pubic bone from the axis of the acetabulum in 

 the several specimens is — 



Bernisscart example ' 

 Atberfield example . 



The length of the femur — 



Bernissart examples " 

 London (type-specimen) " . 

 Atberfield example 



These figures prove a specimen of /. mantelli even greater in size 

 than /. bernissartensis, and the lightness, gracefulness, and smallness 



^ L. Dollo, "Premiere Note sur les Dinosauriens " : Bull. Mus. E. Hist. 

 Nat. Belg., vol. i, pi. ix, fig. 1. 

 '■^ Log. cit., p. 164. 

 3 E. Lydekker, B.M. Cat. Foss. Eep. Amp., 1888, pt. i, p. 202. 



