30 THE ZOOLOGIST. 
NOTES AND VOW Eaiiis: 

AVES. 
Eggs of Red-backed Shrike (Lanius collurio).—Your correspon- 
dent’s suggestion in regard to the variation in the eggs of Lanius 
collurio (Zool. 1907, p. 429), to my mind, is entirely wrong, contrary to 
my own experience, and to what I think is now generally accepted as a 
concrete opinion, vzz. one bird, one type. If Mr. Mussel-White will 
take a trip to Bempton when the cliffmen are “egging,” and get into 
conversation with some of them, they will convince him on this 
point in a very short time. They know from a very lengthy experi- 
ence that in many cases (unless anything has happened to the bird) 
the same type of egg will be found on the same ledge year after year ; 
so well do they know these particular spots that they will tell you 
what type of eggs they expect to bring up. Mr. J. M. Goodall has 
among his exceedingly fine series of eggs of Guillemot (Uria troile) 
the production of several birds extending over a number of years, and 
taken from the same ledges frequented by those particular birds. In 
each case they are all absolutely identical, and obviously laid by the 
same females, and would, I venture to say, convince the most sceptical 
oologist on this all-important and most interesting problem. Those 
who have formed a large series of the eggs of U. troile will appreciate 
the difficulty there is in finding two eggs identical in ground colour 
and marking. It is therefore a comparatively easy matter to trace 
those which are the produce of one female; though they may differ 
slightly in marking the general character is maintained. I have 
proved this conclusively in regard to many species (including Lanuws 
collurio). Among them I may mention Black-headed Gull, Thrush, 
Nightingale, Nightjar, Cuckoo, Kentish Plover, Herring-Gull, Tree- 
Pipit, Blackbird, Kestrel, Redbreast, Lapwing, Richardson’s Skua, 
Stone Curlew, &c. With regard to the Red-backed Shrike, it is well 
known that the eggs of this species vary considerably, but neverthe- 
less are confined to four distinct types (not varieties). There are of 
course intermediate, modified, and extreme types, which may be, and 
should be, termed varieties, or, strictly speaking, varieties of types. 
In a large sertes of these eggs it is quite easy to detect these four 
