PROFESSOR OWEN ON THE GENUS DINORNIS. 125 
rest of the pelvic disk (Pl. XV. fig. 1, 7,7) is bounded externally by the strongly pro- 
duced ridge overhanging the vertical postacetabular plate (Pl. XIV. fig. 1, 62, 7) of the 
ilium, which coalesces with the similarly vertical expanding plate of the ischium (ib. 63). 
The foramen (ib. m) between the ilium and beginning of the ischium is a full ellipse or 
oval. The ischium developes downward a ridge, behind the obturator notch (qg); but 
this does not meet the ridge reciprocally directed upward from the pubis (ib. 64): there 
are impressions of the attachment of a strong fibrous sheet which closed the obturator 
groove behind; and this sheet becomes a thin plate of bone in old individuals of some 
existing Rallines (Tribonyx ventralis, Ocydromus australis). 
The proportions and form of so much of the pubis (64) as is preserved adhere to the 
ralline type of that bone; but the tubercle, prominent below the fore part of the bone 
in most existing Rallines, is not developed in Aptornis. 
I have restored, in dotted outline, the parts of the ischium and pubis broken away 
from the otherwise complete and truly singular and interesting form of pelvis in 
Aptornis defossor. It may aid in future comparisons of this most complex of bones to 
subjoin a list of the parts of the pelvis, conveniently indicated by names, with the 
symbols used to indicate them in Pl. XIV. fig. 1, and Pl. XV. 
The specimens of Aptornis defossor above described are from a cavernous fissure at 
Timaru, Canterbury Settlement, South Island of New Zealand. I am indebted to 
Dr. D. S. Price, of the Crystal Palace, Sydenham, for the much valued opportunity 
of describing, comparing, and figuring them. 
Parts of the Pelvis of Aptornis defossor, Ow. 
a. Acetabulum (the letter marks, in Pl. XIV. fig. 1, the inner aperture). 
b. Postacetabular facet. 
c. Centrum (marking, m Pl. XV. fig. 2, the ridged underparts of the first and second 
sacral vertebre). 
c'. Centrum (marking the unridged underparts of succeeding centrums). 
d. Diapophysis (marking, in Pl. XIV. fig. 1, the diapophysial articular surface). 
e. Subacetabular fossa. ff. Antacetabular part of ilium (Pl. XV. fig. 1). 
g. Gluteal ridge. h. Gluteal process (Pl. XIV. fig. 1). 
z. Ilium (marking, in Pl. XV. fig. 2, the part anchylosed with and overhanging the 
foremost diapophysis). 
id. Interdiapophysial vacuities (marking the six anterior ones). 
1. Postiliac tuberosity. m. Ischiadic foramen. 
n. Neurapophysis; #' in Pl. XV. fig. 1, is the fore part, n* the hind part, of the neur- 
apophysial crest. 0. Ilio-neural orifices. 
p. Parapophyses, ee combine to separate, below, the interdiapophysial vacuities: 
pl. Pleurapophyses,) in Pl. XIV. fig. 1, pl marks the articular surface for the head 
of the first sacral rib. 
