1903. | OSTEOLOGY OF THE CUCULIFORMES. 281 
backwards into an obliquely sloping bar. The pubis is long, 
slender, and much bowed and closely bound to the posterior half 
of the ventral border of the ischium, beyond which it extends for 
some considerable distance. The obturator foramen is bounded 
posteriorly by a broad bar of bone descending from the ischium 
and fusing with the pubis. The pectineal process is reduced to a 
vestigial condition. 
In the form of the pelvis, Cucwus, Coccystes, Scythrops, differ 
but little, save in size, from Cacomantis merulinus. In Scythrops, 
however, the obturator foramen is not cut off posteriorly by the 
descent of a bony plate from the ischium. In all save ¢ ‘acomantis 
and Cuculus the intertransverse sacral foramina are more or less 
completely filled up. 
In Rhopodytes and Hudynamys the mesial border of the extreme 
anterior end of the preacetabular ilium rises to the level of the 
neural ridge as in Geococcyx (text-fig. 46, p. 282). In Taccocowa this 
elevated region extends somewhat further backwards and forms 
a quadrate plate, the free border of which is lightly applied to the 
neural crest. In Crotophaga, Rhamphococcyx, Coua, and Piaya 
actual fusion takes place between this plate and the synsacrum. In 
Centropus and Dromocoecyx the relationship between the fused 
region of the ilium and the synsacrum has become still further 
modified, so that the extremity of the ilium has acquired a T-shaped 
form, the dorsal limb of the cross-piece bridging a widely open 
canalis ilio-lumbalis. A similar canal is of course formed in the 
other cases where the ilia meet the neural crest of the synsacrum, 
but it is inconspicuous. ) 
Further modifications in the form of the pelvis are the 
enormous lateral expansion of the dorsal plane and the short- 
ening of the pubis. In forms like Crotophaga, Coua, or Rham- 
phococcyx, the early stages of the first-mentioned modification 
may be studied. Passing through forms like Centropus and 
Taccocoua, we reach a climax in Geococcyx (text-fig. 46, p. 282). 
Herein the width across the dorsal plane equals the length of the 
synsacrum. This outward extension of the postacetabular ium 
has resulted in the formation of a huge ledge passing far beyond 
the level of the antitrochanter, and finally, at its free edge, 
turning abruptly downwards and then suddenly upwards, back- 
wards, and inwards, like a pair of wings, so that the surface of the 
dorsal plane acquires a peculiar saddle-shaped appearance. Seen 
from the side (text-fig. 47, p. 282) or from below (text-fig. 48, 
p. 282), this overhanging ledge forms an enormous penthouse 
above and slightly behind the ilio-ischiadic foramen. A similar 
modification obtains elsewhere only among certain Rails. It 
appears to be correlated with a terrestrial mode of life, these forms 
flying but little. 
The shortening of the pubis is most marked in Geococeys, 
Piaya, Centropus, and Rhinococeyx, and to a less extent in Coua 
and Crotophaga. 
A large pectineal process occurs in Geococcyx, Cowa, Centropus, 
