88 
Mr. D. A. Bannerman on rare Birds [Ibis, 
worked through what they term the solitarius group of 
Cuckoos in the British Museum, and published their con¬ 
clusions on pp. 642, 643 of 4 The Ibis/ 1919. They remark 
(/. c . p. 643) : “ The relationship of the solitarius group with 
C. clamosus, the Black Cuckoo, which is also found all over 
Africa, is very obscure, as is also the relationship of 
C. solitarius and C. gabonensis . There appears to be a series 
of intermediate forms (which has been called C. jacksoni) 
between C>. clamosus and C. solitarius. There is also a 
series of intermediate forms (called C. mabirte) between 
C. gabonensis and C. solitarius. It is possible that these may 
be regarded either as three separate species intergrading in 
certain areas, or as three species in process of evolution from 
one form within those areas.” I am not at all in agreement 
with these conclusions, believing C. solitarius to be a per¬ 
fect^ fixed race with very distinct young. 
Cuculus gabonensis I believe to be also a fixed race 
with distinct young, having a subspecies Cuculus gabonensis 
mabirce. I shall deal with the status of C. clamosus and 
C. jacksoni later. 
I have now the entire fine series of these forms contained 
in the British Museum spread out before me in addition 
to certain specimens kindly lent to me, from Tring by 
Lord Rothschild and by Dr. van Someren from his private 
collection. 
Cuculus gabonensis gabonensis 
To deal first with Cuculus gabonensis gabonensis : we possess 
fourteen examples in the British Museum showing the com¬ 
plete change of plumage as explained by Air. Bates (Ibis, 
1911, p. 501). 
1 . The first plumage is uniform black throughout (speci¬ 
mens Nos. 3898 and 3904). 
2. The second is the transitional stage, some of the barred 
feathers of the underparts and some of the barred 
chestnut feathers of the throat are appearing amongst 
the black feathers ; the glossy feathers are appearing 
