348 



four other processes succeed this before the one which abuts against the be- 

 ginning of the pubis : this is much thicker and stronger than the prece- 

 ding ones, and it is succeeded by four confluent sacral vertebrae, which have 

 no lower transverse processes. In the Ostrich the transverse processes of 

 the sixth sacral vertebra abut against the part of the innominatum from 

 which the pubis is continued, and the transverse processes of the four suc- 

 ceeding vertebrae abut against the origin of the ischium, parallel with the 

 lower part of the acetabulum ; then a single vertebra without a lower trans- 

 verse process or sacral rib intervenes before these are again developed in 

 succeeding vertebra?, to abut against the posterior part of the acetabulum. 

 The four ribless sacral vertebrae which in the Dinornis are interposed 

 between those which send their anchylosed ribs to abut upon the os in- 

 nominatum anterior to the acetabulum, and those which strengthen in 

 like manner the posterior part of the acetabulum, are very short ; their 

 bodies have coalesced into a single mass of bone, smooth and flattened 

 below, rounded at the sides, and only recognizable as distinct bones by 

 the orifices for the nerves at the sides of the anchylosed mass : these 

 orifices are double, as in the sacrum of other birds*, the two roots of 

 the nerves escaping separately, the motor root issuing by the lower, the 

 sensitive root by the upper orifice. The upper transverse process of the 

 first sacral vertebra is a broad and thick piece of bone, extending from 

 the body and anterior articular process of the vertebra, and having a deep 

 and smooth excavation at its anterior part : in the Ostrich the corre- 

 sponding part is much smaller, and is reticulated by the bars of bone 

 dividing the orifices by which the air is admitted into the interior of the 

 vertebra. 

 1559. A large portion of the right os innominatum, including the entire acetabu- 

 lum of a Dinornis, probably Din. ingetis. This must have come from a 

 bird of smaller size than the one to which the above-described portion of 

 the sacrum belonged. The part of the ilium before and above the aceta- 

 bulum rises with a steep slope and a slight general concavity to meet its 

 fellow above the spinous crest of the anterior part of the sacrum : behind 



* Cyclopaedia of Anatomy, art. Aves, p. 271. The Ostrich is the only exception to this rule with 

 which I am acquainted. 



