
303 
§ 3. Pelvis of Aptornis otidiformis. (Plate LKXXY, figs. 1-3; 
Plate LXXXVI. 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 
“confiuence of yertebre 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 
vertebra as “ sacrum.” 
In Aptornis the sacrum includes nineteen vertebre (Pl, LXX XY. fig. 2, 81-19). 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, leaying 
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 (¢’) 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 (PI. LXXXYV., fig. 1, pi, Pp!) is oval, with the 
small end upward, rather deep, well defined, and supported on an eminence at the appee 
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 oe second ites 
diapophyses constitutes the foremost of the . interdiapophystal holes” (PL LXXXY, 
fig.2,id'). The third pleurapophysis (ib. pl) 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. ‘he fourth is still shorter, and abuts as a parapophysis 
against the distal end of the third, with an extensive bony union above with . sp 
pophysis of its own vertebra. The fifth, sixth, and Bey Sult ae nee ee 
gain breadth, and abut, with complete confluence, against the ilium a 4 ae oe s 
lower margin ; the seventh blends with a smooth ridge-like thickening of t e lower border 
of the acetabulum as it passes to be continued into the oence the ischium (63), ; 
There then follow three sacrals without “ parapophyses;” a side view of these, de- 
