1903. ] OSTEOLOGY OF THE CUCULIFORMES. 271 
Internally the squamosal appears to be visible only in Cuculus 
canorus and Centropus, where it appears as a small triangular 
plate wedged in between the prootic, parietal, and alisphenoid. 
The nasal, judging from the scanty material at my disposal, 
differs slightly in form in different genera, inasmuch as in Cuculus 
and Centropus it is not sufficiently large caudad to cover the 
horizontal plate of the mesethmoid. In Centropus the hinder 
border is produced into a sharp angle, and is rounded in Cueulus 
and Geococeyx. ‘The nostril is holorhinal. 
The lachrymal offers no special features for comment. 
The premavilla is fully ossified only in the skull of Geococeyx. 
Its nasal processes are long and slender, and the median suture 
dividing them extends fax beyond the level of the anterior border 
of the nasal fossa, The maxillary and palatine processes lie close 
together and parallel with one another. 
The mawilla in Geococcyx is elongated and triangular in form, 
and sends backwards from its postero-external angle a long 
slender bar to join the jugal and quadrato-jugal. The body of 
the maxilla is slightly spongy and has the postero-internal angle 
produced backwards and inwards into a maxillo-palatine process. 
The body of the maxilla lodges a barely perceptible antrum. 
The quadrato-jugal is long and slender in Geococcyx; the re- 
lations between the jugal and maxilla cannot be made out, the 
skull having become disarticulated. 
The vomer is absent. 
The palatine does not differ appreciably from that of the adult. 
The pterygoid is rod-shaped, and produced forwards into a sharp 
triangular spine (Pl. XXII. fig. 10), which articulates with a cor- 
responding facet in the mesial border of the palatine. Later this 
triangular process becomes segmented off from the main shaft 
to form the hemipterygoid, which ultimately fuses with the 
palatine. At the present stage this segmentation is faintly indi- 
cated by a shallow furrow on the outer surface of the shaft. In 
the adult, where the fusion with the hemipterygoid is complete, 
the palato-pterygoid articulation is formed by the approximation 
of glenoid surfaces sloping obliquely backwards. 
The dentary and splenial do not differ from those of the adult. 
The coronoid, angulare, and supra-angulare ave all as yet 
distinct. 
iv. THE VERTEBRAL CoLuMN. 
The vertebral column of the Cuculiformes is not marked by the 
same constancy of character which is so conspicuous in the skull, 
In many respects it recalls that of the Coraciiformes, but even 
among the Cuculi relatively wide differences obtain. 
All the presynsacral vertebre are heteroccelous, and all the 
thoracic vertebra are free. 
The cervicals of the smaller Cuculi recall those of Leptosoma. 
The odontoid ligament of the atlas is ossified, The axis vertebra 
is very short antero-posteriorly, and has the neural arches produced 
Proc. Zoou. Soc.—1903, Vou. I, No. X VIII. 18 
