1903.] OSTEOLOGY OF THE CUCULIFORMES. 287 
but the latter at any rate is the direct outcome of adaptation. 
Probably the remarkably specialised condition of the pelvis also 
is adaptive. 
In the accompanying table it will be found that I have arranged 
the Cuckoos on a plan formed of a compromise between that of 
Beddard, based on the pterylography and voice-muscles, and one 
based on the osteology and voice-muscles. The two will be found 
to disagree in many points; and it is on this account that 
I have published the results of my comparison, since it will, I 
hope, stimulate further research by directing renewed attention 
to the anatomy of the discordant forms. 
A. Sternum with single pair of notches ; pectineal process of pelvis vestigial. 
Muscle-formula AXY+, except Hudynamys which has the formula 
ABXY-+. 
. : Cuculus. 
a. Syrinx tracheo-bronchial. 
Muscle-formula AXY+, except eee si 
Eudynamys which has ABXY+. | 77, ae as 
Old World. Sey th pane ; 
b. Syrinx bronchial. i 
Muscle-formula ABXY +. { hated aa 
New World. 
B. Sternum with single pair of notches; pectineal process of pelvis large. 
e. Syrinx bronchial. Cent 
Muscle-formula ABXY-+. { CREEL 
Old World. Dromococeyx. 
C. Sternum with two pairs of notches ; pectineal process large. 
d. Syrinx bronchial. 
Muscle-formula ABXY-+. 
ING MW/@AIGE sacoscop snsoco sone ecocconss Cra ENE 
@OLARWrorlde ene tec eco cei OOUde 
( Rhinococeyx. 
e. Syrinx tracheo-bronchial. FR aaa 
Muscle-formula ABXY-+, except Baenowae 
Z ; ies ypodytes. 
Piaya which has AXY+. Wancinstonius: 
Old World. Taccocoua. 
Piaya. (New World.) 
D. Sternum with two pairs of notches ; pectineal process vestigial. 
f. Syrinx tracheo-bronchial. Che , 
Muscle-formula AXY-+. irysococeya. 
Old World. Cacomantis. 
Mr. Beddard has shown, in tabular form, the points wherein 
the skulls of the Cuculi and Musophagi differ one from another. 
These are not many, and I cannot but think that they are really 
of slight importance. The most striking are the differences 
in the size of the antorbital plate, the position of the maxillary 
end of the quadrato-jugal bar relatively to the tomium, and the 
relation of the mesial borders of the proximal ends of the palatines. 
The desmognathism of the palate seems to me to be precisely 
similar in both forms. If the skull of Z’wracus, for example, be 
compared with that of Cowa, it will be found that the chief 
difference lies in the more spongy nasal septum of the latter, 
Proc. Zoot. Soc.—1903, Vou. I. No. XIX. 19 
