PROFESSOR OWEN ON THE GENUS DINORNIS. 257 



p 4. The bodies of the four vertebrse without lower transverse processes (b) are flatter 

 below in the smallest pelvis than in p 4. The vacuity at the sides of these vertebrae, 

 into which the posterior aperture of the acetabulum opens, is relatively much smaller 

 in the p 5 than 'mp4; but the two transverse processes of the twelfth and thirteenth 

 vertebrce which abut against the posterior part of the acetabulum are absolutely much 

 thicker in p 5 than in p 4. For example, the first of these transverse processes in the 

 larger pelvis p 4 is one inch seven lines long and one and a half line broad : in the 

 smaller pelvis it is ten lines long and four lines broad. Such differences are not mani- 

 fested in the pelvis of individuals of the same species in other birds : they are associated 

 in the present instances with minor differences in the shape of the acetabulum, espe- 

 cially of its posterior and inferior border, and in the relative breadth of the bodies of 

 the posterior sacral vertebrae ; the latter, however, might be a sexual difference. Seven- 

 teen of the sacral vertebrae are preserved in the specimen p 5, and the expanded spi- 

 nous plate of the posterior ones is more perfectly preserved than in the preceding 

 specimen, p 4. The following are some of the dimensions of p 4 and p 5, compared with 



those of the pelvis of an Emeu : — 



Dinornis,p4. Dinorms,p5. Dromaius. 

 In. Lin. In. Lin. In. Lin. 



Length of the pelvis 110 



Greatest breadth at post-acetabular protuberance ..69 



depth at the origin of pubic bones .... 5 6 



Breadth of the pelvis at the posterior part of the ilia . 3 6 



After a summary of the characters which the different pelves of the Dinornis present 

 in common, it is obvious that the genus recedes furthest from the Struthious type and 

 makes the nearest approach to the tridactyle GrallcB in the structure of this part of the 

 skeleton. 



There remains to be determined, to which of the species of Dinornis already esta- 

 blished by the bones of the leg, the three specifically-distinct pelves are to be referred. 

 "We cannot take the relative lengths of the pelves and femora of existing Strutkionida 

 as a guide, on account of the disproportionate length of the pelvis in them as compared 

 with the Dinornis. The pelvis of the Bustard is also relatively longer than in the Di- 

 nornis. The size of the acetabulum is not so good a guide as in MammaUa, because it 

 is always relatively larger than the head of the femur in Birds : thus, although the ace- 

 tabulum in the portion of the pelvis p 2 is larger than the head of the entire femur 

 / 2, the size of the post-acetabular articular prominence corresponds sufficiently 

 closely with the articular surface upon the neck and trochanterian enlargement of that 

 femur to render it probable that they belonged to the same species, if not individual. 

 The fragment of the huge pelvis p 1 might well have belonged to a Dinornis of the 

 largest stature. The two remaining specimens of pelvis are too small to be adapted to 

 the femur/ 12, but of the species indicated by that and the tarso-metatarsal bone m 3, 

 there appears to be a small portion of a pelvis in the present collection. 



