THE IGUANODON AND H YL^EOSAURUS. 
283 
Length along the middle of the shaft 27 inches. 
Length to the distal inner process 32 
Circumference of the distal or tarsal end .... 25 
middle of the shaft . . . . 18 
upper part 20 ^ 
Probable length of this tibia when entire, 4 feet. 
A fragment of the shaft of a tibia found with the above, is 23 inches in circum- 
ference. The distal end of another tibia, from Sandown Bay, is 27 inches in circum- 
ference. As a contrast to these gigantic remains, I may state, that bones of the ex- 
tremity occasionally occur so small, yet so compact, as to suggest the probability 
that they may belong to distinct species ; but at present I have not been able to de- 
tect other characters which would warrant such an inference. A left femur in my 
possession, from Rusper in Sussex, is 14^ inches long; circumference of the shaft 
6 inches ; this therefore is but one-fourth the size of the specimen from Brook. The 
lower portion of a thigh-bone, which in the characters of its condyloid extremity 
entirely agrees with all the recognized femora of the Iguanodon, is but 3^ inches in 
circumference round the condyles, and but 2 ^ round the shaft immediately above them ; 
the total length of this femur, when entire, could not have exceeded 4^ inches. 
In general the circumference of the shaft of the thigh-bone immediately below the 
base of the inner trochanter, is nearly equal to half the length of the entire bone ; for 
example, the large right femur from Sussex in the British Museum, which is 3 feet 
8 inches long, is 21 inches round the shaft. But there are exceptions to these pro- 
poi’tions ; thus the femur from Brook Point, presented by me to the Hunterian Mu- 
seum of the Royal College of Surgeons, is relatively shorter, for it is only 3^ feet 
long, while the circumference of the shaft is 24 inches. The thigh-bone of the Maid- 
stone fossil is of more slender proportions. The tibia is about one-tenth shorter than 
the corresponding femur ; and the fibula somewhat shorter than the tibia. With the 
view of affording a general idea of the dimensions of the known parts of the skeleton 
of the Iguanodon, to whieh the largest femur in my possession belonged, the following 
list, calculated from the average size of numerous specimens, is subjoined ; the length 
of the corresponding bones in the Maidstone fossil is added for comparison. 
Iguanodon from the Isle of Wight. Maidstone Iguanodon. 
Femur, length of 4 feet 8 inches. 2 feet 9 inches. 
Tibia 4—1 ....2—6 
Fibula 3 — 8 .... 
Humerus 3 — 2 ....1 — 8 
Clavicle 4 — ....2 — 4 
Scapula 3 — 4 . ... 2 — 1 
Metacarpals 2 — 2 ....1 — 2 
Ilium 3 — 10 . ... 2 — 4 
Metatarsals 1 — 11 ....1 — 2 
Ungueal bones 5f . . . . 3| 
