74 MR. C. W. ANDREWS ON THE SKULL AND 
ilia, and at the bottom of this there are traces of one or two pairs of interosseous 
foramina. The ilia terminate posteriorly in prominent ilio-caudal processes, which 
project some distance beyond the last fused caudal. From these processes there runs 
inward and forward on either side a ridge which, after continuing a short distance 
parallel to the vertebral axis, runs downward and outward to the upper angle of the 
ischiadic foramen; this ridge seems to be the hinder part of the ilio-lateral ridge, 
which is so strongly developed in many birds, ¢. g. Rails. Anterior to it the dorsal 
surface of the ilia are evenly convex from side to side. 
Viewed from the front, the most conspicuous points are (a) the relatively large size 
of the centra of the sacral vertebre; (8) the extreme lateral compression, the ilia 
meeting in the iliac crest at an angle of not more than 10°; (y) the very narrow slit- 
like opening of the ilio-neural canals; (8) the very prominent supra-trochanteric crests 
which, from this point of view, completely hide the whole of the dorsal surface of the 
postacetabular region. 
In a posterior view the supra-trochanteric crests and anti-trochanters completely 
conceal the whole pre-acetabular region. Behind them we have first the median ridge 
of the sacrum, on each side of this a shallow groove, and external to this again the 
ilia, the regular downward curve of which forms an arc of a circle, and below these 
the ischia curving outward and diverging one from another. This portion of the pelvis 
has been crushed laterally, but not to any great extent. 
Looking at the pelvis from the side (Plate XVI. fig. 2) it will be seen that the 
acetabulum is considerably in front of the middle of the pelvis, and measured from 
the middle of the acetabulum the pre-acetabular portion of the ilium is 140 mm. in 
length, the postacetabular 265 mm., or roughly as 10 to 19. The acetabulum itself is 
nearly circular in outline, its antero-posterior diameter being slightly the greater 
(acet.); through it the arches of the lumbo-sacral vertebre are visible. Its antero- 
superior border forms a projecting lip, and the anti-trochanter, the lower border of 
which is excavated by a narrow fossa, is large and very prominent, and, except for a 
narrow groove, is continuous aboye with the supra-trochanteric crest. Anterior to the 
acetabulum is the slightly concave and nearly vertical gluteal fossa of the ilium, below 
the edge of which the centra of the pre-acetabular sacral vertebre are visible. 
The ischiadic foramen (is,f.) is very large and roughly ovoid in outline. Just within 
its antero-superior angle, and bordered anteriorly by the anti-trochanter and superiorly 
by the edge of the ilium, there is a pocket-like fossa, which internally is separated by a 
slight ridge from the mass of bone formed by the fusion of the processes of the true 
sacrals. The anterior edge of thei schiadic foramen is continued downward as a ridge 
crossing the shaft of the ischium and terminating below in a prominent process 
(styliform process), against the inner side of which the pubis was in close contact, thus 
enclosing an obturator foramen (0./.) which forms a narrow oval opening extending from 
beneath the posterior half of the acetabulum as far back as the front of the ischiadic 
foramen. 
