0.0. M arsh—The Order Theropoda. 335 
THE Petvic ARCH. 
he pelvic bones in the Theropoda have been more gener- 
ally misunderstood than any other portion of the skeleton in 
Dinosaurs. The ilia, long considered coracoids, have been 
since usually reversed in position; the ischia have been 
regarded as pubes; while the pubes themselves have not been 
considered as part of the pelvie arch. 
Fortunately, in the present specimen of Ceratosaurus, the 
ilium, ischium, and pubes are firmly codssified, so that their 
identification and relative positions cannot be called in ques- 
tion. The ilia, moreover, were attached to the sacrum, which 
was in its natural place in the skeleton, and the latter was 
found nearly in the position in which the animal died. Th 
es of Ceratosaurus and of Allosaurus are shown in 
late XT. 
The ilium in Ceratosawrus has the same general form 
as in Megalosaurus. In most of the other Theropoda, also, 
this bone has essentially the same shape, and this type may 
be regarded as characteristic of the order. In Creosaurus, 
the anterior wing is more elevated, and the emargination 
sch 
hina well backward, and for the last half of their lengt 
forward, a : 
Seen from the front, they form a Y-shaped figure, which varies 
in form in different genera. The upper end i 
a a large surface, and the ischium by a smaller attachment. 
he united distal ends are expanded into an elongate, massive 
foot, as shown in Plate XI, which is one of the most peculiar 
and characteristic parts of the skeleton. le 
The pubes of Jegalosaurus have not yet been identified, 
but there can be little doubt that they are of the same general 
omen as an “abdominal hremapophysis and h 
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