228 MR. W. P. PTCEAFT ON THE MOEPHOLOGT AND 



ilium of an exceedingly thin plate of bone with a jagged free edge. It arises in the- 

 region of the 5th post-sacral vertebra, and is continued backwards from this point. From 

 the superior border of the ischium there arises a similar plate of bone of corresponding 

 length. In very old birds these two jagged-edged plates nearly meet, foreshadowing 

 the formation of the ilio-ischiadic foramen of the Ncognatluv. 



The interobturator process, botli in Casuariiis and Lrommus, is well marked. 



The ischia, both in Dromons and Casuarius, are more or less rod-shaped and 

 very distinctly bent inwards towards the middle ; this is a point of great significance 

 when considered in connection with the ischium of lihea. The ischium is roughly 

 1 -shaped. Its vertical process articulates with (in the young) and eventually 

 fuses with the pre-ilium, forming the lower half of the anti-trochanter. Antero- 

 ventrally it articulates with and eventually fuses with the pubis, the fusion with the 

 pubis taking place much earlier than is the case with the vertical process and the ilium. 



The pubes are very slender relatively, with a strong outward curve in Dronueiis and 

 Cas%(arms casiLarius, straight or only slightly curved in the remaining species of 

 Castiarkis. In the nestling they do not extend backwards as far as the level of the 

 free end of the post-ilium. In the adult they extend beyond this, reaching nearly to 

 the end of the ischia. They are always free posteriorly in the dried skeleton, 

 connected by cartilage in the living bird with the ischia. 



The pectineal process seems to be formed for the most part by the descending process 

 of the ilium. It reaches its greatest development apparently in Bromwus, hut in a 

 pelvis of Casuarius casuarius it is only slightly less in size. In the remaining species 

 of Casuarius it is but feebly developed. 



The outline of the pre-ilium differs, but the series of adult skeletons in the Museum 

 collection is not sufficiently large to enable any reliable data to be drawn from 

 comparisons. 



Sjiecific differences in the form of the pelvis of Casuarius may possibly be found, but 

 I think it extremely doubtful. The collection of adult skeletons which forms the 

 subject of this paper is not nearly large enough to afford the material necessary for 

 such a task. 



The pelves of the C. henneiti group seem distinguishable from the C. casuarius group 

 by reason of the relatively longer and narrower post-acetabular ilium. We have 

 no adult skeletons of the C. unappendiculatus group. 



In Rhea the form of the pelvis is unique, but, as will be shown, is probably a direct 

 modification of the Uromaeine type. 



In the nestling the pre- and post-acetabular ilia are subequal in length. The latter 

 is abruptly truncated caudad, and rests by its postero-ventral angle upon the closely 

 approximated ischia, to be described presently. The supra-trochanteric process is 

 but feebly developed, and the anti-trt)chauter is but slightly below the level of tiie 

 neural crest of the synsacrum. The post-acetabular ilium is long and narrow and 



