PROFESSOR OWEN ON THE GENUS DINORNIS. 247 
iliac bones are continuously confluent. The ischium, receding from the acetabulum, 
expands vertically, and converts the ‘ischiadic notch’ into a foramen by junction with 
the ilium; near its acetabular origin it sends down a feeble prominence to denote the 
hind boundary of the ‘ obturator foramen,’ which is thus a mere notch widely commu- 
nicating with the space between the ischium and pubis, beyond which the latter bone 
extends for some distance in both the Dido and the Solitaire. 
§ 7. Caudal Vertebre. 
The free, or proper, caudal vertebre of Dinornis parvus are eleven in number; but 
the tenth has coalesced with the eleventh (Pl. LIV. figs. 2-7). The first caudal 
resembles the last sacral in the vertical extent and general thickness of the transverse 
processes; but these have not the length of those of the otherwise similar vertebrae in 
which such processes are confluent with the ilia. The under surface of the centrum is 
irregularly grooved lengthwise, not smooth as in the antecedent vertebra; the neural 
arch sends off a pair of short, thick, obtuse processes, representing a bifid neural spine, 
which seems to have had ligamentous junction with the hind part of the neural arch in 
advance, a median prominence of which has been continued by ligament into the inter- 
space of those processes. 
The centrum of the second caudal vertebra shows the same irregular inferior grooving 
as the first; the loss of size in the second is chiefly due to the minor development of 
the transverse processes, from each of which slightly project a diapophysial and para- 
pophysial prominence. ‘The neural arch here also sends off a pair of short, but more 
divergent, obtuse processes, defined by an anterior notch. ‘The third caudal loses 
breadth; but this dimension continues the same to the seventh caudal inclusive. The 
transverse processes gradually diminish; and the indication of their double nature 
disappears at the sixth caudal; the short stumpy bifid character of the neural spine 
is continued, with slight diminution of size, to the eighth caudal inclusive. In the 
ninth it is represented by a single tubercle ; in the tenth it disappears and the neural 
canal is there closed. A fine vertical line descending from a puncture, which may 
have transmitted a nerve-filament from the end of the neural axis, and a transverse 
pair of notches on the under part of the centrum are the indications of the primitive 
development of the seeming terminal vertebra from two cartilaginous rudiments. The 
ossified confluent result exceeds in length that of any of the antecedent caudals, and, 
besides the absence of neural spine, gradually narrows to a rough termination of 2 lines 
inferior breadth; the sides of the eleventh vertebra converge to an upper ridge (ib. 
fig. 3). 
The base of the terminal coalesced vertebre (ib. fig. 7, 10, 11) is more rough and 
irregular than in the two antecedent caudals; in the rest of these vertebre a similar 
