292 



PETRIFACTIONS AND THEIR TEACHINGS. CHAP. III. 



LlGN. 61. 



LEFT FEMUR OF THE IGUANODON; 



ANTERIOR ASPECT. 



(^ nat. size.) 



a. Outer trochanter. 



b. Median trochanter. 



c. Inner condyle. 



d. Outer condyle 



e. Anterior intfa-condyloid 



fissure. 

 /. The head of the femur. 



of the Iguanodon was, for the first 

 time, developed. 



In the Case before us, there are 

 several splendid specimens of this 

 gigantic member of the skeleton 

 of the Iguanodon some of pro- 

 digious magnitude ; others that 

 must have belonged to reptiles 

 but recently hatched, or else to a 

 very diminutive species of the 

 same genus: the former is the 

 most probable conclusion. 



FEMUR OF THE IGUANODON. 

 Wall-case C (ante, p. 227). The 

 femur of the Iguanodon is remark- 

 able from the combination of 

 mammalian characters which it 

 presents in its well-marked head 

 and neck, trochanters, condyles, 

 and medullary cavity. The head 

 (Lign. 61,/.) is hemispherical, and 

 projects inwards over the shaft, as 

 in the mammalia ; there is no 

 appearance of a ligamentum teres. 

 A flattened lateral process or tro- 

 chanter (a) forms an external 

 buttress or boundary to the neck 

 of the bone, from which it is sepa- 

 rated by a deep, narrow, vertical 

 fissure. 



The shaft of the bone is sub- 

 quadrangular ; a slightly elevated 

 ridge, produced by the union of 

 two broad, flat, longitudinal sur- 

 faces, indicating the attachment of 

 powerful muscles, extends down 

 the middle of the anterior face, 

 and diverging towards the inner 

 condyle, gradually disappears. 

 The shaft terminates below, in 

 two large, rounded, laterally-com- 



