PHYLOGENY OF THE PALZOGNATHA AND NEOGNATHA., 2717 
b. Post-acetabular ilia closely approximated, the neural spines at most only 
barely visible between the closely approximated innominates ; no supra- 
trochanteric process; ischia widely separated from post-acetabular ilium; 
obturator foramen and fissure confluent ; post-sacral vertebre of the 
synsacrum welded into a large laterally compressed mass, bent down so 
as to bring the neural crest to the level of the ventral border of the post- 
TU : Sea 6 Te fee ee en Aptenyan 
B. Pubes anchylosed caudad mk one raneihien or He ‘eehittmn: 
c. Post-acetabular ilia widely separated from ischia, and from one another 
in the mid-dorsal line; pubes fused caudad (a) with the ischia and (6) 
with one another in the mid-ventral line; the synsacral vertebre appear- 
ing below the level of the ventral border of the iium . . . . Struthio. 
d. Post-acetabular ilia anchylosed with ischia, and with one otis in ‘the 
mid-dorsal line; pubes anchylosed with ischia caudad; ischia closely 
united in the middle line one with another throughout almost entire 
length (unique) ; the post-sacral vertebr of the synsacrum atrophied . Rhea. 
Key to the Species. 
RueEa. 
a, Pre-ilium not projecting forward beyond the last thoracic vertebra and rib, 
which forms the limit of the synsacrum cephalad . . . . . . . . ~ RK. americana. 
6, Pre-ilium projecting forward conspicuously beyond the last thoracic vertebra 
aNGcribE. 0 poe ced eee Cet ameter wotege sl Bi stm ow slat cq tl Mee ONES USM UMRAETALCH ONY NCH Os 
APTERYX. 
A. Width across anti-trochanter equal to or less than the width of pre-acetabular 
ilium at widest. 
a. Pre-acetabular ilium of great width, with a strongly arched dorsal border, 
and large laterally expanded antero-ventral angles; width across pre- 
acetabular ilia at widest part=to length of ischium, and far exceeding 
length of post-acetabular illum; post-acetabular ilium with a sudden 
widening at its free end; breadth of pre-illum at widest=breadth across 
yneIneNEE De Gy 6 56 OG O18 9 5 O06 0 6 9 8 oo HRCI ARIES 
B, Width across anti-trochanter always greater than width of pre-acetabular 
ilium at widest; post-acetabular tapering caudad; breadth of pre-ilium at 
widest less than breadth of anti-trochanter. 
6. Pectineal process large ; five lumbar vertebre. 
a’, Post-acetabular lium with a concave ventral border, and a slight notch 
immediately behind the anti-trochanter . . . . . . .. . . A. haasii. 
'. Post-acetabular ilium with straight or convex ventral border ; no notch 
behind theraninetochanten sais sential wera etin tome a sneer 16d.) 0mvent. 
c. Pectoral process small; four lumbar vertebre . . . . . . . . . . A. a, mantelli. 
you. xv.—Ppartr vy. No, 22.—December, 1900. 2Q 
