202 THE ESSEX NATURALIST.
towards abnormal plumage may be inherited, and although more
evidence is required yet there are at least two Essex instances
which serve to support the idea that this is also the case with
eggs, namely those, of the Robin and the Spotted Flycatcher.
CONCLUDING REMARKS.
As each part of the paper is self-contained there remains
but little to add. The purpose of this contribution is to place the
subject on a County foundation and the necessity for this has
been demonstrated by the lack of information and still further
by the incomplete nature of the data which exist. Both field
and museum worker can assist in the necessary reparation. The
former has the greater opportunity. The locality will always be
stated. The first and last dates of the period under which the
bird has been under observation should always be taken and also
a detailed description on the first occasion. It should be stated
if partial, complete partial or complete and in addition if the
eyes, bill, legs and feet are affected or not. In the case of partial
birds it should be stated if symmetrical or asymmetrical. Any
change in the condition of the plumage should be noted. Should
tho bird breed, the condition of its eggs and offspring should be
remarked. The sex should be noted, wherever possible. The
museum worker will obviously make a detailed description of the
plumage and also determine the sex. Information on the above
lines should be elicited from the obtainer of the specimen.
It is important that evidence should be obtained of the rela-
tion of heterochrosis to moult and in this connection the impor-
tance of dates will be realised. It may be that both sexes are
equally affected, but it is impossible to come to a decision until
such time as the sex of a sufficient number of affected birds has
been determined.
In the case of eggs, descriptions of these should be made, with
a statement if they have a tendency in the direction of any of the
four phases of heterochrosis, and if the birds are normal.
In conclusion I take the opportunity to thank the following
for the assistance I have received in the preparation of this paper :
Miss G. Lister, Mr. H. C. S. Halton, Dr. G. Carmichael Low,
Messrs. J. H. Owen and Percy Thompson, and Prof. Sir J. A.
Thomson.