1903. ] OSTEOLOGY OF THE CUCULIFORMES. 269 
The supraoccipital is extremely short antero-posteriorly, and 
is deeply cleft in the middle of its superior border. Its external 
lateral border fuses with the lateral occipital; within the cranial 
cavity it is bounded by the epi- and opisthotic. The small size 
of the supraoccipital recalls the skull of the Owls, but this of 
course is but a coincidence. The character will doubtless be 
found to obtain in the Kingfishers, Bucconide, and Capitonide, 
which have many characters in common with the Cuckoos, 
The provtie does not appear externally, Within the cranium 
it occupies considerable space, forming the floor of the mesen- 
cephalic fossa, as well as a considerable portion of the lateral walls 
of the basin-like metencephalic fossa. It entirely excludes the 
squamosal from the cranial cavity. 
The epiotie is only partially ossified, and in such a way that its 
boundaries cannot be made out. 
The opisthotic has fused completely with the prootic. 
The basisphenoid is not visible externally, being underlaid by 
the basitemporal plate. Concerning its internal boundaries, 
nothing satisfactory can be gathered from the two skulls in the 
National Collection, the younger being damaged, whilst in the 
more adult skull it has fused with the neighbouring bones. 
The alisphenoid, in the younger of the two skulls, is not yet 
completely ossified. As a result, between the external ventral 
angle and the squamosal there is a wide gap, which extends 
inwards below the inferior alisphenoid border, dividing its outer 
moiety from the basisphenoid. This gap, when viewed from 
without, is seen to be filled up by the prodtic. Its supero- 
external angle is produced outwards to form the postorbital 
process. 
The orbito-sphenoid is not yet ossified in these skulls. 
The presphenoid has fused with the basisphenoid. 
The mesethmoid, in the two skulls now under consideration, 
is yet incompletely ossified, forming but a linguiform plate; the 
interorbital septum formed by the backward extension of the mes- 
ethmoid having been represented only by cartilage. ‘The anterior 
border of the linguiform plate is sharply truncated so as not to 
extend beyond the level of the free end of the parasphenoidal 
rostrum below and the anterior extremities of the frontals 
above, ‘This truncation occurs at the cranio-facial fissure, which 
has cut the mesethmoid into two parts: the one forming the 
linguiform plate just described, which ultimately forms the 
interorbital septum; the other, the septwm nasi, which in these 
skulls is yet cartilaginous. 
The cranio-facial fissure appears to be peculiar to the neo- 
gnathine (Carinate) skull; but traces thereof are appa rently to be 
met with in the Paleognathe (Ratitz), inasmuch as, in the skulls 
of nestlings of Dromeus and Rhea in the Museum Collection, the 
ossification of the mesethmoid commences, as in the Neognathe, 
by the formation of a more or less linguiform plate, and this has 
its superior border deeply excised, at a point exactly corresponding 
