272 PETRIFACTIONS AND THEIR TEACHINGS. CHAP. III. 



probability, assign the fossil in question to the pelvis of the 

 Iguanodon. 



" This fine portion of pubis is of an inequilateral triangular 

 form, 16 inches in its longest diameter, 9J inches across its 

 base, or broadest part, 6 inches across its narrowest part. 

 The fractured surface of the bone near the acetabulum, is 3| 

 inches thick. The acetabular depression is seven inches across, 

 a proportion which corresponds with that of the acetabular 

 concavity in the ilium, and with the size of the cavity in 

 which the head of the Iguanodon's femur must have been 

 received. One angle of the, cavity corresponding with the an- 

 terior one in the Varanus, is raised ; a broad and low obtuse 

 ridge bounds the rest of the free margin of the cavity. The 

 smooth labrum exchanges its character near one of the frac- 

 tured edges of the bone for a rough surface, which indicates 

 the commencement of the symphysis. In the apparent absence 

 of the perforation below the acetabular depression, the present 

 bone agrees with the Crocodilian type." Brit. Assoc. Rep. 

 1841, p. 136. 



ISCHIUM 1 Wall-case 0. Upper shelf. : Near the specimen 

 last described, there is a fragment of a large lamelliform bone, 

 (labelled ^ff^-), which Professor Owen considers to bear most 

 resemblance in its general form and slightly twisted character 

 to the Ischium, with traceable modifications intermediate to 

 those presented by the extinct Goniopholis, and modern 

 Varani and. Iguance. I had often attempted to discover the 

 true character of this bone when in my possession, but could 

 not arrive at any satisfactory conclusion respecting it \ it 

 struck me as more nearly resembling a bone of the arm than 

 of the pelvis, and that it might possibly be the humerus oi 

 an unknown species or genus of saurians ; its surface and 

 texture differ from those of the bones of the Iguanodon. 



CAUDAL VERTEBRAE AND H^EMAPOPHYSES. Wall-case C, lowest 

 compartment. These elements of the spinal column have been 

 discovered from time to time in numerous localities of the 

 Wealden strata ; the caudal vertebrae collected by myself, or 

 submitted to my examination, amount to several hundred 

 specimens. The most splendid example beyond comparison 

 is the series of six anterior caudal vertebrae with their pro- 

 cesses almost entire, and three chevron-bones or hsemapophyses. 



