351 



Apteryx. There is likewise another difference in the relative position of 

 the acetabula as compared with the Ostrich : in this bird those cavities 

 are so situated that their posterior wide orifice exposes to view the neural 

 arches and spinous processes of the intervening sacral vertebrae. In the 

 Dinornis only the lower part of the bodies of the corresponding vertebrae 

 are seen by looking directly into the acetabulum, and below these we 

 have the open cavity of the pelvis : the Apteryx and Emeu resemble the 

 Dinornis in this respect. The body of the third sacral vertebra is cari- 

 nate below in the Bustard, and none of the vertebrae abut by their trans- 

 verse processes against the anterior part of the acetabulum. 



The present pelvis of the Dinornis, when compared with the portions 

 of the larger pelves, Nos. 1558 to 1560, presents so many differences be- 

 sides those of size, as to leave no doubt about the specific distinction of 

 the birds to which they belonged. 



The first sacral vertebra in the smaller pelvis has a narrower and deeper 

 body, and there is not the deep excavation on the anterior part of the 

 upper transverse process. The sacral ribs, as well as their anchylosed 

 analogues, the transverse processes which succeed them, come off higher 

 up than in the large pelvis. The lower border of the ilium is thin, and 

 does not form a broad convex surface, increasing the width of the pelvis 

 anterior to the acetabulum, as in the large Dinornis : the four inter- 

 acetabular vertebra? without inferior transverse processes are carinate 

 along their under surface, not flattened as in the great Dinornis. The 

 upper facet of the posterior part of the ilium is more horizontal, and 

 forms a right angle with the vertical facet : this is also divided from the 

 anterior concave wall of the ilium, as in the Ostrich, by an angle formed 

 by an obsolete ridge : the articular prominence behind the acetabulum is 

 relatively longer in the axis of the pelvis, but less deep in the smaller 

 species. The root of the ischium where it forms the upper part of the 

 obturator notch is concave, and an angular process descends towards the 

 pubis, forming a well-marked posterior boundary to the notch. In this 

 character the smaller pelvis more resembles the pelvis of the Emeu than 

 does that of the larger one ; but the ischial process does not quite reach, 

 as in the Emeu, the pubic bone. The ischium resembles, in its gradual 



