the Structure of Hierococcyx ^c. 605 
Cuckoos, containing the genera Eudynamis, Scythrops, and 
Phcenicophaes, resembles the Cuculine series. T have already 
indicated"^ the general likeness that exists between the 
syringes in these three genera and that in the genus Cuculus. 
There is, in fact, a very close resemblance; but the full 
Garrodian muscle-formula and the complicated pterylosis 
led rae to place the group containing these genera midway 
between the Cuculine and the Centropine series. I have no 
reasons for doubting the correctness of that placing ; and I 
may observe that Fiirbringer f seems inclined to allow this 
arrangement, and to admit with me that Eudynamis and its 
allies are perhaps to be looked upon as ancestral forms from 
which the Cuculine series on the one hand and the Centropine 
on the other are to be derived. We should, therefore, expect 
to find in this group — or at least we should not be surprised 
to find there — a syrinx of a rather more primitive style of 
structure than in the hj^pothetically modified Cuculinse, As 
a matter of fact, what we do find in the Eudynamis group 
are syringes shewing precisely the same characters as in the 
C/Uculine group. This, however, is no bar to the derivation 
of the one series from the other. In my paper upon the 
anatomy of Scythrops % I made, as I find on re-examina- 
tion of the syrinx of that bird, a slight error. I stated 
erroneously concerning Scythrops that the intrinsic muscles 
of the syrinx were attached to the second bronchial semi-ring. 
But I now find that they were attached to the third of 
those rings. 
Among the allies of Eudynamis we therefore find syringes 
constituted upon two plans that are to be found in the 
Cuculine series. But since the Phoenicophainse have some 
claims to be regarded as ancestral to the Centropinae, Ave 
should expect to find some hints of a Centropine arrange- 
ment of the rings and muscles of the lower part of the 
windpipe. It is one of the objects of the present communi- 
cation to shew that there is a hint of a development into 
* P. Z. S. 1885, p. 172. 
t Unters. z. Morph, a. Sjst. d. Vogel (Amsterdam, 1888). 
I P. Z. S. 1898, p. 44. 
