366 PROFESSOR OWEN ON THE GENUS DINORNIS. 
origin of the much larger extinct(?) brevipennate Rallines of New Zealand, it may 
be remembered that our own Coots and Waterhens are poor fliers compared with most 
water-birds, 
§ 3. Pelvis of Aptornis otidiformis. (Plate XLII. figs. 1-3; Plate XLIII. figs. 1-4.) 
My materials for the description of this instructive part of the skeleton are derived 
from the smaller species (Apt. didiformis), and were obtained from Wanganui, North 
Island of New Zealand. 
Referring for the definition of the bone called “sacrum” to my ‘ Anatomy of Verte- 
brates,’ “Aves,” vol. ii. p. 29, I find it most convenient to adhere to the character of 
“confluence of vertebree in connexion with the pelvic arch.” In the ‘ Archetype &c. of 
the Vertebrate Skeleton’ are discussed the characters by which the homologies of 
the twenty “sacral vertebre” of the Ostrich e.g. with the lumbar and caudal ver- 
tebree of Reptiles and Mammals may be determined; therefore I need not be misunder- 
stood if, to make plain, or easily comprehensible, the characteristics of the pelvis of the 
extinct ground-birds of New Zealand, I continue to speak of such confluent series of 
vertebree as “sacrum.” 
In Aptornis the sacrum includes nineteen vertebre (Pl. XLII. fig. 2, s1-19). The 
under surface of the confluent centrums shows well-defined modifications: it is pinched 
into a median ridge in the first three; the ridge is then, as it were, scooped off, leaving 
a smooth concave surface or mid channel along the next six centrums, beginning and 
ending in a point (fig. 2, ec’). From the hind point (c’) a broadish obtuse ridge runs 
along the next seven centrums, which gradually lose breadth. The seventeenth centrum 
suddenly expands; and those of the eighteenth and nineteenth have the form of broad 
depressed plates moderately concave across; the lateral confluent productions of the 
vertebree being defined by two pairs of small vertical canals. 
The pleurapophyses of the first and second sacral vertebre retain their moveable 
joints. The cup for the head of the rib (Pl. XLIL. fig. 1, p/, pl) is oval, with the small 
end upward, rather deep, well defined, and supported on an eminence at the upper part 
of the centrum, nearer the fore end in the first than in the second sacral. ‘The surface 
for the ‘‘tubercle” is small, flat, cut obliquely at the fore part of the end of the 
diapophysis, which expands above to contract bony union with its successor and with 
the overlying ilium (62). The unossified space left between the first and second sacral 
diapophyses constitutes the foremost of the ‘“ interdiapophysial holes” (Pl. XLII. 
fig.2,7d'). The third pleurapophysis (ib. p/) is short, straight, expanded, and confluent 
at both ends, broadest at that which underlies and is soldered to the ilium, beyond 
which it does not extend. The fourth is still shorter, and abuts as a parapophysis 
against the distal end of the third, with an extensive bony union above with the dia- 
pophysis of its own vertebra. The fifth, sixth, and seventh parapophyses lose length, 
gaia breadth, and abut, with complete confluence, against the ilium a few lines from its 
