HETEROCHROSIS IN ESSEX BIRDS AND THEIR EGGS. 195
Complete partial 0
Partial . . .. 0
Total . . 1
Ref.: The Birds of Essex (Christy).
The very limited number of Essex examples of this pheno-
menon supports what has been experienced of the subject as a
whole. The above cases are in accordance with the view of the
Hon. W. Rothschild that green birds are subject to xanthism.
It is of some interest that the Chaffinch should have been affected
completely with the exception of the white bars on the wings,
and this lends colour to the view that xanthism may be a stage of
albinism in certain plumages. The case of the Yellow Bunting
shows that xanthism may be congenital and that in such cases
normal birds may be found in the same brood.
ERYTHRISM.
House Sparrow. Passer d. domesticus (L.). A variety with a
more or less brilliant chocolate throat was found to be com-
mon near Chelmsford. One was captured on 4 Jan., 1877
and another with it, very brilliant, on 26 Feb., 1878. Ref.:
The Birds of Essex (Christy).
Cuckoo. Cuculus c. canorus L. Three examples of the hepatic
plumage have been recorded. Ref. : The Birds of Essex
(Christy); The Zool., 1895, pp. 257-63.
Common Partridge. Perdix p. perdix (L.). One Perdix montana,
rufous variety. Several Perdix montana, rufous variety.
Ref. : A History of the Birds of Essex.
It has been impossible to make use of the categories under
this head. The colours of the three species affected are worthy
of note as they are so far removed from those, namely, green and
yellow, which are said to be generally affected. Each of the
phases described is recognised. It is stated that the black of
the chin, throat and upper breast of the House Sparrow is at
times partially chestnut. It is probable that the birds described
above were affected along such lines. The hepatic, presumably
liver-coloured, plumage is said to be assumed only by the female
Cuckoo. One example, described by Mr. Christy, was sexed
as a male, which would appear to have been an error. The rufous