104 ' Proceedings of the Royal Physical Society. 
This is a specially interesting series. Nos. 5 and 9 are greyish in colour, 
moderately well speckled with brown. No. 5 is slightly darker: than No. 9 
at the broad end, but they fit in well as a pair with the general theory of 
common parentage. No. 16 is an egg of a different type, smaller in size 
and pale bluish-green with regularly distributed small grained brownish 
speckling. _ It is probably the egg of a separate bird. On comparing it with 
the eggs of series X., from the same area and of same year’s taking, 
and particularly with H 14 and H 15 which were found about the 
same time (24th and 29th June), we still find this egg distinctive. 
Whilst it approaches these two more nearly in appearance, its ground 
colour is of a deeper blue and the amount of brown speckling is rather 
greater. It is also a smaller ege. 
XUI.—Two eggs, taken at West Drayton (Lank of Colne) Middlesex. 
Museum No, Foster. Date when taken, 
M 6/14. 4 . Reed Warbler . ; . Ast July 1912 
M 15/5 . . Sedge Warbler . . 11th July 1912 
These eggs are of a pale, sandy colour, with light brown speckling 
running in places into fairly large blotches. The brown colouring is 
moderately sparse, generally, and absent at the narrow end of the egg 
which is rather pointed looking. The resemblance of the two eggs is rather 
striking, and they are probably the offspring of the same bird. Two foster 
species are involved. 
When single eggs of the foregoing thirteen series taken at random are 
placed alongside, the interesting fact becomes evident that with one 
exception no two resemble each other, even approximately, as the members 
of the sets themselves do. Further, a comparison of sets from the same 
locality, by the method of taking an egg at random from each group, yields 
eges readily distinguished by their colour in each case. There are two 
sets from Budworth Mere, Cheshire, of the same season, and these are 
quite distinct when laid alongside, the difference being more marked than 
any verbal description can bring out. 
There are six sets from Huntingdonshire, representing three different 
years’ takings. Sets IX. and XII. are rather alike, but. their resemblances are 
not so great as the members of any of the sets considered in this paper. 
They constitute the one exception quoted above. The other examples can 
all be distinguished at a glance from these and from each other. 
What conclusions can be drawn from these facts ? 
