OF THE IGUANODON, AND OTHER SAURIAN REMAINS. 
139 
Pectoral or anterior extremity. — No certain indications of the humerus, radius, or 
ulna, have been obtained. A large imperfect humerus, and portions of antebrachial 
bones of the Lacertian type are in my collection ; but there are no data to show that 
these may not have belonged to the Megalosaurus, or other Saurians, whose remains 
are intermingled with those of the Iguanodon in the Wealden strata. There is one 
large subcylindrical bone (Plate VIII. fig. 5.) in the Maidstone fossil that probably be- 
longs to the upper extremity, but I have not been able to develope its characters 
satisfactorily. Of the carpal bones nothing is known, but there are several perfect 
examples of the metacarpal, digital, and ungueal (Plate VIII. figs. 14. 1 7. 23. 26.). A 
series of five metacarpals proves that the anterior extremity possessed the normal 
character of the Lizards. The metacarpals (figs. 14. 23. 26.) are long and slender, 
as in the Iguana. 
Pelvic arch. — Fragments of enormous bones, evidently belonging to the pelvis, are 
the only certain remains of this part of the skeleton hitherto known ; for the two 
large hatchet-shape bones (Plate VIII. fig. 28.) in the Maidstone specimen, and which 
I referred provisionally to the pelvis*, have not been examined with sufficient accu- 
racy to warrant any positive conclusions ; it is even possible that they may be found 
to belong to the pectoral arch. It is, indeed, difficult, from the small bones and pro- 
cesses of the existing Lizards, to detect analogies under the modifications they assume 
when enlarged perhaps more than twenty times, in the colossal skeletons of the ex- 
tinct genera, and presenting corresponding deviations from the typical structure of 
the recent reptiles ; and I must acknowledge the disappointment it has often been 
my lot to experience, when, after hours of close examination and comparison of some 
of the fossils with apparently analogous recent bones, I have found myself unable to 
establish their relation. 
Pelvic, or posterior extremities. — The osteology of the thigh, leg, and foot of the 
Iguanodon, presents important peculiarities, and with the exception of the tarsus, is 
well elucidated by numerous perfect specimens of the femur, tibia, fibula, metatarsal, 
digital, and ungueal bones, of several individuals of different ages. The thigh bone 
(Plate VIII. fig. 1.) offers remarkable deviations from the corresponding bone of the 
Iguana, and of the other recent Lizards. The shaft of the bone is irregularly qua- 
drangular, and has near the middle an apophysis, or trochanter (Plate VIII. fig. 1 . b) 
on its tibial aspect; it terminates proximally in a bold round head'f~, with a distinct 
compressed trochanter on its fibular aspect, and distally in two largely-developed 
condyles, separated, anteriorly as well as posteriorly, by a deep groove or furrow. 
The outline of this bone in the figure (Plate VIII. fig. 1.) displays its essential characters. 
The enormous magnitude of the Iguanodon is strikingly shown in the colossal pro- 
portions of the femur. The largest thigh-bone in my collection is twenty-four inches 
* Wonders of Geology, vol. i. p. 396. 
t I have not detected any depression in the head of the bone for the insertion of a ligamentum teres. 
MDCCCXLI. 
U 
