58 
by a bridge of land to the Continent, when the rise of the general 
land level bad led to the severing of the connections of Scotland with 
Scandinavia and Ireland with Scotland, and thus many central 
European species never reached Ireland. The ab. flavescens Buchanan- 
White is the ordinary form in Central and South Europe and in all 
the southern range of the insect. 
In Step’s book on Forest Trees we find that the Scots fir, Pinas 
sj/lvestris, is a native of Scotland, and though formerly found in 
England it died out completely and was replanted. The replanting 
began in Hampshire and the neighbouring counties in 1776, but the 
trees on Leith Hill in Surrey may be descendants of those planted a 
century earlier by John Evelyn in the grounds of Wotton. If the 
afforestation took place in this way it must have been a slow process. 
With regard to Ireland, Step states that it is and must be considered 
a true native, though according to the Cybele Hibernica, no satisfactory 
evidence of its survival exists, the last forests having been cut down 
900 years ago. 
It is certain that the south of England was repopulated by the 
insect after the direct land connection with the continent of Europe 
was broken, and it is also certain that a large part of Ireland was 
repopulated, and the question arises as to the source of this fresh 
population. 
Some interesting facts are to be gleaned from the older works on 
entomology. Albin (1712 1720) gives figures of many of the more- 
conspicuous geometers, but none of B. piniarius. Wilkes (1778) 
also leaves it out. It is probable that it was unknown to either of 
these authors. 
Donovan (1800) describes the cream form, ab. flavescens, and figures 
the male only. He says this rare aud curious species of Phalaena has- 
been for some years admitted to the cabinets of English Natural 
History, but on the most dubious authority. That it is an inhabitant- 
of Great Britain is, however, now ascertained, for in the summer of 
the present year, about the last week in June, it was observed in great- 
plenty in a fir wood at Crathis on the north bank of the river Dee, in 
Mearnshire, Scotland, by George Milne, Esq., of Surrey Place, 
Walworth. They seldom fly low, and are consequently taken with 
some difficulty. 
Again, Haworth, in 1803, “ Lep. Britannica p. 278, says having- 
only German specimens the description is omitted. The species is 
well known, T. P. Neale, having lately found it in England, and W. 
J. Plooker, F.L.S., in Scotland, “ in exceeding abundance in the fir 
woods on the Hill of Kinnoul, by Perth, in the middle of June,” and 
continues with accurate description of flight, etc. 
From this we can only conclude that it was at that date really rare 
in southern England. Though observers were few in Scotland, all 
our information comes from that country, its very existence in southern 
England being in dispute, though many good naturalists were working 
in places where it abounds now. Rare insects, such as Acronycta 
alni and Notodonta trimacula were well known, and so conspicuous a 
day-flying insect could not possibly have been overlooked. 
Even in 1841, Humphreys and Westwood, though figuring the 
xxii.-xxiii. 
