1054 
MR. J. W. HULKE ON THE OSTEOLOGY 
1st. toe. Ilnd. toe. Illrd. toe. IVth. toe. Vth. toe. 
Lengths millims. millims. millims. millims. millims. 
Metatarsals. .. 63* 69* 56* 
1 st phalange. 23* 25- 17* 
2rd phalange. 17* 14* 17* 12* 
3rd phalange. 21 - 13‘5 8‘ 
4th phalange. ,. 23’5 8 ‘ 
5th phalange. ., . # b # 47 - 
The sacrum, as in all true dinosauria, differs in the greater number of vertebrae 
composing it from that of Saurii and Crocodilini. The Ilium closely imitates that of 
Aves in the great extension of its prseacetabular part—a part which in Saurii and 
Crocodilini exists only as a mere rudiment. 
The Ischium in respect of its length and slenderness and its direction parallel to the 
lower border of the post-acetabular part of the Ilium differs entirely from that of 
Lizards and Crocodilians and closely resembles that of Aves, as noticed first by 
Professor Huxley. The slender rod-like part of the pubis {post-pubis, O. Marsh) 
directed backwards parallel to the Ischium is obviously the homologue of the pubis in 
Aves and in Saurii. Its broad prcepubic or prseacetabular plate {prcepubis, O. Marsh) 
has no homologue in Saurii; in Aves it exists as a mere rudimentary tubercle. Its 
homology with the bone called pubis in Crocodilians deserves consideration. 
The Ilium, Ischium, and Pubis all contribute to the formation of the acetabulum, as 
I believe occurs in all other dinosauria of which the pelvic bones are known, Omo- 
saurus being no exception to this, for the suggestion that in this dinosaur the pubis 
articulates only with the Ischium and is thus “ seemingly ” excluded from the aceta¬ 
bulum^ obviously arises from a misconception of the homologies of the several parts 
of the pubic bone. A comparison of its pubis with those of Iguanodon Mantelli, 
Hypsilophodon Foxii , and certain American dinosaurs must make this apparent to 
every unbiassed mind. 
The different proportions of the femur and tibia in Hypsilophodon and Iguanodon 
Mantelli have been noticed. In the former it is longer than the tibia, in the latter 
it is shorter than the tibia. In Hypsilophodon the inner trochanter is nearer the 
proximal end than it is in Iguanodon Mantelli, and it is also more pointed than in 
this. The differences in the anterior intercondylar groves in these two dinosauria are 
striking. The tibia is more slender than in Iguanodon Mantelli. The Avian resem¬ 
blances of femur, tibia, and proximal row of tarsalia are very striking. The pes differs 
from that of Iguanodon Mantelli notably ip. the presence of a fourth functional toe. 
This alone would, I submit, suffice to exclude it from the genus Iguanodon in which 
the pes has but three functional toes. In having four functional toes and the rudi- 
* Owen, R., ‘Mezozoic Reptilia,’ part ii., p. 64. 
