48 
PIElilD.E. 
The Larvae are smooth and covered with a slight down, 
slightly tapering at the extremities. All the known European 
species are green, with lighter lateral stripes. Their food-plants 
are mostly various low-growing species of Legiminoscc. 
The Pupae are straight, and terminated by a point anteriorly. 
Obs. — This is one of the most interesting genera of Butterflies, 
not only on account of the extreme beauty of the species, but also 
of their habits and geographical distribution. The genus is spread 
over a very wide area, but is not found in the hotter parts of the 
earth, its place being apparently occupied in intertropical regions 
by the genera Callidryas and Tcrias, some species of the latter 
genus bearing a striking resemblance to those of the present. 
Many species of the genus Colias are confined to the northern 
regions ; some are found exclusively within the Arctic circle — a 
curious variety of Colias Hecla, having been taken in 187G by 
Capt. Feilden and Mr. Hart at the surprising latitudes of from 
78° to 83° N. ! For an account of the insects collected by these 
Arctic explorers in 1876, I must refer my readers to Mr. M'Lachlan’s 
highly interesting report, which appeared in the ‘ Journal of the 
Linnean Society,’ No. 74, May 23rd, 1878.* Besides Colias, three 
other genera of butterflies were found to be represented in these 
regions : “ Thirty-five specimens of gaily-coloured butterflies,” 
writes Mr. M‘Laciilan, “were procured, belonging to certainly five 
distinct species. It may safely be asserted that there are desert 
regions in the tropics that would not fnrnish an equal number.” 
The other genera found were Argynnis, Lyccena, and roiyommatus. 
It is now a generally received opinion, and one supported by actual 
geological discovery, that the climate of the Arctic regions was, 
immediately previous to the Glacial Epoch, not only milder than 
it is at present, but actually warm, and supported a luxuriant 
vegetation, traces of large trees, both deciduous and evergreen, 
having been proved to exist in these high latitudes.! Now it is 
believed by many zoologists that, during the Pliocene period, a 
■'= “ Eeport ou the Insecta (including Arachnida), collected hy Gapt. Feilden 
and Ml'. Hart between the parallels of 78° and 83° N. latitude, during the recent 
Arctic Expedition.” By Eobert M'Lachlan, F.E.S., F.L.S., &c. 
I Wallace, on ‘ The Geographical Distribution of Animals,’ vol. i., pt. i., 
p. 70. London, 1870. 
