OF HYPSILOPHODON FOX1I. 
1051 
this part a broad bar-like plate extends forwards and downwards, and an extremely 
slender long rod passes backwards parallel with and supported by the corresponding 
ischial bar, which it nearly equals in length. I cannot certainly say that the ventral 
ends of the pubis were symphysially joined, but the appearances make this probable. 
The bottom of the bony acetabulum was defective. 
Femur (Plate 75; Plate 78; Plate 80).—This is a much stouter bone than the 
humerus. Its proximal end has a sub-globular head borne on a stout short neck, 
the axis of 'which makes nearly a right angle with that of the shaft; and a pro¬ 
minent outer trochanter between the upper part of which and the shaft is a deep 
narrow fissure. Behind the head is a small pit, and in front between the neck and 
the outer trochanter is a larger depression. The distal end has the usual condylar 
shape. The outer condyle is longer and stouter than the inner. Both project 
strongly backwards, and are here separated by a wide deep intercondylar groove, 
the outer border of which is formed by a narrow ridge which divides the inter¬ 
condylar groove from a deep but much narrower groove in which the upper end of 
the fibula moved, the ridge itself being received in the interval between the fibula 
and the outer tibial condyle in flexion of the leg on the thigh. The anterior inter¬ 
condylar groove is wide and shallow, contrasting strongly in these respects with 
the deep narrow, almost tunnel-shaped, anterior intercondylar groove in Iguanodon, 
as known in L Mantelli, I. Frestwichii, and I. Seelyi. The shaft of the femur 
appears to be twisted owing to the alteration in the aspect of its surfaces, that which 
at the proximal end is external becoming at the distal end anterior. It is also 
bent, its upper longitudinal outline being a convex curve. The cross-section at the 
middle is rudely prismatic. Nearer to the upper than the lower end of the bone 
at the inner and posterior aspect of the shaft is a compressed triangular, in the 
best-preserved specimens, remarkably long-pointed inner trochanter, the apex of which 
is directed towards the distal end of the bone. At the inner side of this trochanter 
is a pit. 
Tibia (Plate 80, fig. 2; Plate 81, fig. 1).—This bone in Hypsilophodon is longer 
than the femur, the opposite of that which obtains in Iguanodon. A nearly 
perfect tibia of Hypsilophodon measures 23*25 centims. long, the length of the femur 
of the same skeleton does not exceed 18 centims. The proximal end of the tibia 
shows a division of the articular surface into two condyles, which project posteriorly 
and are here separated by an intercondylar groove. A large prsecnemial crest 
projects from the upper part of the shaft in front of the external condyle. The 
cross-section of the shaft is prismatic. The distal end is expanded and shaped into 
two malleoli, of which the outer and posterior is longer and thinner, and the inner 
and anterior is shorter and stouter. These are separated in front by a wide shallow 
groove, which ascends a slight distance on the anterior external surface, and below 
ends behind at a salient angle where the inner and posterior surfaces meet. The 
outer border of the distal half of the tibia is impressed in its anterior aspect by the 
