(awe) 
the normal emergences were only some three or four weeks 
as pupz, these late ones were seven, eight or even nine weeks. 
It is almost certain that the darkness does not depend on the 
late date, but that it does, either on the prolonged, pupal 
period, or on the low temperature the pups were subjected to 
during the maturation of the imago. A temperature of 47° 
to 60° must certainly be low for an insect that expects the 
temperature of an August on the Riviera, even when all allow- 
ance be made for their being possibly deeply hidden under 
stones, etc., in their natural habitats. Looking to the results 
of Mr. Merrifield’s experiment, I entertain little doubt that 
the effective agent for darkening is the low temperature, and 
not the prolonged pupal period, though it may be difficult to 
disentangle the two causes in these or in any other instances. 
“The effect of cold is here to produce darkening as it appears 
to be in a majority of temperature experiments. 
“It is to be specially observed that the dark effect is to make 
the hyerana form darker and the marginata form darker, with- 
out any indication that it has the slightest tendency to make 
the pale from hyerana into the dark form marginata. These 
are special varieties, selected no doubt after they appear on 
the same grounds as dark and pale forms might be selected, 
but not arising in the same way as ordinary darkening (in- 
crease of pigment) does. One or two specimens, especially the 
two darkest December males, strongly suggest that whatever 
caused the darkening, also produced a less robust specimen. 
If this be so then the darkening is due to injury by cold, not 
to a more perfect, because prolonged, maturation.” 
Mr. F. Merririztp made some further observations on the 
effects of temperature on seasonal forms, resulting not only in 
difference of colour, but in difference of structure. 
PaLtmarctic ANTHOCHARID AND Mexiraip Burrerries.— 
Miss M. E. Founrarne exhibited a number of Anthocharid 
and Melitzid butterflies from various localities in the pale- 
arctic regions, showing a wide range of variation. They 
included the following :— 
Preris napi, 39 9: 1 from Algeria, and 2 var. flavescens, 
summer brood, from Médling, near Vienna. Pontia daplidice, 
showing an extreme form of var. bellidice, from Aix-en- 
