336 MR. W. K. PARKER ON THE OSTEOLOGY OF BAL/ENICEPS REX. 
margin of the pelvic roof in the Heron, is feebly developed in the skeleton of this 
Baleniceps. The narrowness of the entire pelvis, and especially the contracted waist- 
like part, before the bone expands to articulate with the os femoris, is precisely what we 
find in all the true Ardeine birds, including Cancroma. But in the Storks the first 
thing that strikes the eye is the broad, expanded, foliaceous condition of this 
part of the skeleton. The narrow little pelvis of Botaurus minutus (so much like that 
of the Crake and Water Rail) is at once seen to be the diminutive counterpart of the 
same structure in the Balzniceps. We shall see, when we come to the bones of the 
feet, that Ralline affinities are not absent from this aberrant ‘ giant,’ whilst such rela- 
tionship appears in the structure of that more normal ‘ dwarf ’—the little Bittern. 
The pelvis of the Baleniceps at its narrow pre-femoral ‘ waist’ is 1 inch and 3 
lines wide ; but it is 2} inches across the iliac crests where they rest upon and overhang 
the sacral ribs. The breadth across the pelvis behind its articular surfaces for the 
great trochanters is 3 inches and a line, being exactly the width of the widest part 
behind, which is one-third of an inch in front of the blunt in-turned terminal tips of 
the iliac bones. The margin of the pre-femoral part of the ilium is rather wide, 
(Pl. LXVII. fig. 27/) and the bone itself here is not very concave, but passes rather 
steeply down for two-thirds of its width, to become more horizontal near the lower and 
outer margin. There is a large crescentic emargination on the front of the ilium, and 
the inferior and outer sharp boundary of this wide notch does not pass so far forwards 
as the upper and inner. 
Half an inch behind the sacral rib there arises a sub-marginal muscular ridge which 
is crescentic, and runs backwards nearly to the acetabulum. This latter cup-like 
articular cavity is not perfected by bone, there being in the skeleton an internal oval 
passage as wide as the head of the thigh-bone. The anterior and upper two-thirds of 
this scooped articular ring is formed by the ilium ; the rest belongs to the pubis below 
and to the ischium behind. Above and behind the ‘ acetabulum’ is the slightly con- 
cave oval articular surface for the great trochanter; it passes obliquely upwards, 
outwards, and backwards. Exactly behind this part is the large sacro-ischiadic 
notch, or rather foramen—it is irregularly oval (Pl. LXVI. fig. 1 in.), its inferior margin 
being rather angular ; it is one inch long—and behind it is the concave line of junction 
of the ilium and ischium, which is one inch and a line in extent. 
The outer margin of the post-femoral part of the ilium is rounded and smooth; the 
bone then passes inwards and downwards to unite with the ischium below. There is 
a notch between these (coalesced) bones at the posterior end. The posterior inner 
margin of each iliac bone receives the rib of the last sacral vertebra and then passes, 
with a very elegant concave outline, bevelled, rounded, and smooth, to its extreme 
outer tip. This terminal end of the ilium lies on a lower plane than the upper and 
outer margin ; so that, on aside view, the end of the ilium is very oblique, as is also the 
sinuous sharp posterior margin of the ischium (Pl. LXVI. fig. lism). The inferior 
