256 PROFESSOR OWEN ON THE GENUS DINORNIS. 



in the Bustard. The body of the third sacral vertebra is carinate below in the Bustard, 

 and none of the vertebrse abut by their transverse processes against the anterior part of 

 the acetabulum. 



The smaller pelvis of the Dinornis, p 4, when compared with the portions of the 

 larger pelves, p \, p2, presents so many differences besides 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 (PI. XX. fig. 2.) has a narrower and 

 deeper body, and there is not the deep excavation on the anterior part of the upper trans- 

 verse process : I do not lay much stress on the fact that the lower transverse processes 

 of the first two sacral vertebrae retain the condition of ribs articulated to depressions at 

 the upper part of the intervertebral spaces {ib. a) ; but every other part of the present 

 pelvis manifests the characters of maturity. These ribs, as well as their anchylosed ana- 

 logues, 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 vertebrae without inferior transverse processes {ih. h) 

 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 (PL XX. fig. 2. c) : 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 re- 

 sembles, in its gradual expansion and straight direction, that of the larger species, and 

 the more perfect condition of the smaller pelvis proves that the extremity of this bone 

 {ih. e) projects freely backwards, as in the Apteryx and Emeu. 



The portion of a somewhat smaller pelvis, p 5 (PI. XIX. fig. 3. PI. XX. fig. 4.), than 

 the preceding is less complete, but manifests characters which prove it to belong to a 

 distinct species of Dinornis, and apparently to an older bird, since the second sacral rib 

 on the left side is anchylosed to the vertebral interspace. This anchylosis sufficiently 

 demonstrates that the smaller pelvis is not of a younger bird than the larger one ; and, 

 besides the difference of size, there are the following differences of configuration : — In 

 the smaller pelvis the second and third sacral ribs arise nearer the lower surface of the 

 bodies of the vertebrae, a character by which the smallest pelvis approximates the largest 

 one, from which it differs, in having the bodies of these vertebrae relatively less broad 

 and flat. The extent occupied by the four posterior orifices forming the interspaces of 

 the lower transverse processes of the third to the seventh sacral vertebrae inclusive, is 

 three lines greater in the smallest pelvis, p b, than in the one next in the order of size, 



