STUBBS : A BLUE EGG OF THE LAPWING. I05 
Page 101. 
M. 
Unionicola crassipes. 
Mull. 
Ventral surface. $ 
X —37 
N. 
Three last segments of palpi. 
O. 
Genital area, g . 
140 
P. 
Arrhenurus caudatus. 
de Geer. 
Dorsal surface g 1 X 
—37 
A>. 
Palpi of g X —100 
R. 
Dorsal surface $ 
X —35 
S. 
Genital area. £ X - 
-38 
T. 
Arrhenurus maculator . 
Mull. 
Dorsal surface. $ 
X —35 
U. 
Genital area. ? X 
-40 
V. 
Atractides anomalus. 
Koch. 
Ventral surface. $ 
X —55 
w. 
Arrhenurus alabator. 
Mull. 
Petiole of $ x — 
87 
ON A BLUE EGG OF THE LAPWING. 
By FREDK. J. STUBBS. 
[Read 30 th October 1915.] 
T HE egg now exhibited was picked up by Mr. Gilbert 
Debenham, on 1st April 1915, between Theydon Bois 
and Abridge. It was not near a nest, and had obviously been 
sucked by a crow. In districts where Lapwings are numerous, 
I have met with similar eggs on two occasions, and have heard 
of a few others, all found empty. 
The ground-colour of the specimen in question may well be 
likened to that of a Starling’s egg, and the dark markings are 
smaller than is usual in normal specimens. Such eggs are, of 
course, very conspicuous, and cannot well escape the eyes of 
nest-robbing birds. 
The subject is an interesting one. Very little has been done 
in the study of the colours of eggs since Dr. Sorby’s researches 
in 1875 (P.Z.S., 1875, pp. 351-365). By the aid of spectrum- 
analysis, he proved the existence of seven colouring matters, 
of which two only need be mentioned here. One is the substance 
which he called “ oorhodeine,” found in brown and red eggs : 
the other is “ oocyan,” a constituent of blue shells. Both appear 
to be present in greenish-brown eggs, such as those of the Nightin¬ 
gale, Pheasant, Lapwing, etc. Sometimes, the oocyan is absent ; 
H 
