232 MR. W. P. PYCRAFT ON THE MORPHOLOGY AND 
the pre-ilium varies, but I think that this, in spite of variation, combined with other 
characters may be relied on. 
Apteryx australis seems to stand alone in the great width of the pre-acetabular 
ilium, a width due to a highly arched dorsal border and a very considerable lateral 
expansion of its antero-ventral border, A rather sinuous post-acetabular ventral 
border and a sudden widening of the post-acetabular ilium caudad are combinations 
apparently peculiar to this species. In A. haastii the pre-ilia are sharply truncated 
forwards, and the pre-ilium is generally broader in proportion than in A. owent. The 
post-acetabular ventral border appears to be concave. 
A, australis mantelli appears, superficially, not to be very readily distinguishable 
from A. oweni. The chief differences appear to lie in the smaller pectineal process and 
broader ischia of A. australis mantelli. 
The pelves of Dinornithide and of the Apyornithide very closely resemble one 
another, and differ from all other flightless members of the Palwognathe in that the 
post-acetabular region of the pelvis is flattened out into a large, pentagonal plate, nearly 
as broad as long. ‘This is made up partly by the great length of the transverse 
processes of the synsacral vertebre, and partly by the great widening of the dorsal plane 
of the ilia—a widening only feebly represented among the Palwognathe elsewhere 
in Struthio. 
In the relations of the ischium and pubis the two pelves now under discussion most 
nearly resemble Apteryx. Apteryx, however, differs in one respect, in that in this 
genus the obturator fissure and foramen are confluent. In the Dinornithine pelvis 
the foramen is shut off from the fissure. The pectineal process is large in Apteryx, 
very small and wanting in the Dinornithine pelvis. 
In the Dinornithide the sacral are more or less easily distinguishable from the post- 
sacral. In the Zpyornithide this is not the case. 
In the Dinornithide the post-sacral neural spines lie in the middle of a deep fossa, 
the floor of which is formed by the upwardly directed neural spines. In the adult this 
fossa is closed more or less completely by a bony roof formed by tabular lateral 
expansions from the crest of the neural spines. Caudad, however, this closure is not 
quite complete: a pair of lateral slits run up on either side of the median neural 
plate, from behind forwards; the extent of these slits decreasing with age, but never 
entirely disappearing. 
In Apyornis the roofing of the fossa is ample: a double row of foramina only 
excepted, which run from behind forwards to the crista transversa. 
The pelvis, both in Dinornithidw and Alpyornithide, is relatively much shorter in 
proportion to its width than in the other Palwognathe. 
