OSTEOLOGY OF THE DODO. 59 
preceding vertebree: they gradually diminish in depth to the last, without loss of breadth. 
The diapophyses proceed obliquely outward and backward, are lamelliform, about 9 
lines in length, and intercept oblong cavities of the same extent and direction, into which 
open the orifices (ib. fig. 2, 0) noticed on the upper surface of that part of the pelvis. 
The articular surface of the body of the last sacral is transversely elliptic, 4 lines by 
2 lines, and very slightly convex. ‘The outlet of the neural canal, above it, is circular, 
and about a line in diameter, the whole vertical extent of the last sacral being 5 lines, 
while that of the first sacral is 2 inches 2 lines. 
The ilium is divided, as usual, into two parts by the ridge on its upper or outer 
surface (ib. fig. 2, 7), extending obliquely backward to behind the acetabulum—the an- 
terior division being narrower and concave, the posterior broader and convex but in a 
minor degree. The anterior (slightly thickened) border of the ilium is curved with the 
convexity forward, extending 8 or 9 lines in advance of the fore part of the neural spine 
of the first sacral vertebra. The ilia almost meet above that of the second and third 
sacrals, with which they coalesce, and then diverge to the oblique boundary ridge, 
which is thence continued, in some with an angular bend, more directly outward. 
At this angle the bone is so confluent with the sacrum that the orifices leading 
to the ileoneural canals’ are almost or quite obliterated. These canals are, here 
(ib. ¢ 7), the longitudinally extended cavities intercepted between the fore parts of 
the ilia and the continuous coalesced sacral spines and diapophyses, widening to 
their anterior outlets. The extent of that part of the ilium in advance of the 
acetabulum is 3 inches 8 lines; the breadth at its middle part is 2 inches. As 
the ilium approaches the acetabulum it increases in thickness, and is grooved at 
the outer margin by a vessel which leaves impressions of its ramifications upon the 
upper concave surface of the bone (ib. fig. 2, 62). The acetabulum (ib. @ @) is cir- 
cular, 11 lines in the diameter of its outlet, 9 or 10 lines in that of its inner circum- 
ference, being widely open, as usual in birds, towards the cavity of the pelvis; the tro- 
chanterian surface (ib. ¢ ¢) above the acetabulum is elliptic, with the long axis length- 
wise, 9 lines by 6 in its diameter, with its upper border sharp and produced; the 
anterior border (ib. 4) of the acetabulum is slightly produced ; the position of this ar- 
ticular cavity is about midway between the fore and hind ends of the pelvis. The 
oblique external ridge of the ilium terminates in the outer margin of the broader part 
of the bone (ib. 7’), 7 lines above the sharp and prominent margin of the trochanterian 
surface (ib. ¢). The ilia have diverged from each other for the extent of an inch and a 
half behind the beginning of the boundary line (ib. 7), which interval is occupied ex- 
teriorly by lateral ossification from the neural spines to the diapophyses of that part of 
the sacrum: the mesial borders of the ilia (ib. fig. 2, 62’) slightly converge to the 
fifteenth sacral vertebra, where they are separated by an interspace of 1 inch, and then 
again diverge to the last sacral; they coalesce with the diapophyses (ib. fig. 2 d d). 
* Owen, ‘Anatomy of Vertebrates,’ 1866, vol. ii. p. 32. 
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