XXVil 
The Proportions of the Sexes in Migration.—Many observa- 
tions show that both sexes are present, but far more extensive 
data are required in order to establish the proportions. In- 
asmuch as the males commonly emerge earlier than the 
females, extensive collections should be made on each day 
of the whole period of migration. Col. Manders states that 
of 60 C. pyranthe of the February flight, 75 per cent. were 
males, while Mr. Wickwar agreed with him that the flight 
‘in November and December were almost all females.” 
Col. Manders thought that the predominance of males might 
be explained by the female larvae being starved by the scanty 
foliage of the drier months. His final conclusion was that 
“the migratory instinct, originally due to a necessity for the 
increase of the species, is now become a means of preventing 
its undue propagation” (p. 706). 
VARIATION IN ANDRENA ROSAE AND A, TRIMMERANA.—In the 
absence of the author Prof. PouLTon read the following paper 
by Dr. R. ©. L. Perxrys, F.R.S., and exhibited a long series 
of specimens illustrating Uicsea 
The Andrena rosae of Saunders’ latest work included three 
species—two being seasonally dimorphic—for which the 
following names are here used. 
1. A. rosae Panz. (summer brood). 
A. eximia Sm. (spring brood). 
= teutonica Alfk. 
— yar. spinigera, part. K. Saund. 
9. A. trimmerana Kirb. nec Auct. caet. (summer brood). 
— rosae, part. EK. Saund. 
= anglica Alfk. 
A. spinigera Kirb. (spring brood). 
3. A. jacobi Perk. (H.M.M., lvii, 1921, pp. 39, 40). 
— trimmerana Auct. nec. K. 
var. scotica Perk. 
var. johnsont Perk. (E.M.M., l.c.). 
A. jacobi, the well-known, common and almost ubiquitous, 
single-brooded species, universally known as trimmerana in the 
literature of over 100 years, does not vary much in the South 
of England, except when changed by the parasite, Stylops. 
