382 MR. J. H. GURNEY ON THE ECONOMY OF THE CUCKOO. 
late Mr. Henry Stevenson and others thought the organ naturally 
had a hairy lining. The matter was set at rest by Mr. Stevenson’s 
sending a Cuckoo’s gizzard to Professor Huxley, who decided that 
they were undoubtedly the hairs of some caterpillar, which, by the 
action of the gizzard, perforated the lining of the stomach, and 
somehow became arranged in a zone-like form, wanting root or 
natural termination. The same arrangement of hairs has been 
found in the Edolio Cuckoo of South Africa, Oxy loplius serratus 
(Sparr), by my late father’s correspondent, Mr. Ayres, and in some 
of the Australian Cuckoos by Gould. Macgillivray figures the 
stomach twice to show the hairs thrust into its epithelium, but his 
plate is rather small. 
Plumage. 
The plain plumage of the British Cuckoo would not seem to give 
much room for variation; but even here this anomalous bird presents 
a distinct kind of dimorphism when young, for it sometimes has 
a rufous plumage, and sometimes a very dark plumage. These 
phases are distinguishable before it leaves the nest, and are still more 
marked when the Cuckoo is eight or nine weeks old, indeed the 
extremes of red and brown might he taken for immaturity in two 
different species. Very early in their life, nine out of ten young 
Cuckoos begin to show a white occiput, and this white feather some- 
times spreads until more than half the crown is white too, amounting 
in one or two cases to albinism. As in Blackbirds and Bing Ouzels 
the partial absence of the dark pigment in the feathers shows itself 
first and most often about the head. We are told that this white 
spot is rarely, if ever, found in the nearly allied Himalayan Cuckoo 
(Fauna of B. India, vol. iii. p. 206), and its absence is a good 
specific character of the Asiatic species I should say. One cannot 
doubt that it is the rufous, and not the dark nestling Cuckoos, 
which up to the Spring following their birth, not very infrequently 
present a bright chestnut-brown colour, accurately compared by 
Howard Saunders to a rich female Kestrel. They are then called 
Hepatic Cuckoos, and are more often females than males. 
A young Cuckoo obtained at Moscow in September appeared to 
