ANTHROCEEID SPECIES. 541 



the stress of its organic environment is less potent, the insect being 

 slowly modified to become fitted to its new surroundings, and at last 

 defied almost the whole insect fauna to follow it. That it is suited to 

 its environment is certain, for in the most inhospitable regions A. 

 exulans is to be sometimes seen, literally in millions. Both these 

 theories assume that A. exulans existed in the lowlying lands, and if 

 this were so, the species must have taken on its present form before 

 the British Islands were separated from the continent of Europe, and 

 probably before the great break, which now separates the great 

 mountain-chains of Asia from those of Europe, occurred in the 

 neighbourhood of the Caspian and Ural Seas. If, however, we accept 

 either of these theories, and suppose that not A. exulans, but a pro- 

 genitor of the species, inhabited the lower ground, we have the 

 remarkable fact that this ancestor has developed into a practically 

 identical form over a vast area of the world, and maintained a 

 particular facies in all the different directions in which the specialisa- 

 tion of the species is going on. 



In Anthrocera purpwalis we have a species that is not strictly 

 limited by altitude or latitude, nor by an arctic or sub-arctic flora. It 

 occurs at the sea-level in Scotland, Ireland, Scandinavia, Russia, 

 Germany, France, Switzerland, Austria, Turkey, Greece, Italy, Asia 

 Minor and Central Asia. It extends from the sea-level, through all 

 intermediate elevations, until it has reached 7,000 ft.-8,000 ft. — 

 Mont de la Saxe 7,000 ft., Cogne 6,500 ft., Le Lautaret almost 8,000 ft., 

 Heiligenblut 7,000 ft., Kokand district 7,000 ft., and the defile of 

 Chakhisnarden, in the Pamirs. Wide as is its distribution, however, 

 there is a roughly governing factor, the species is rarely found off a 

 calcareous soil, and if it be, it is usually near enough to show traces of 

 the characteristic flora of chalk and limestone districts. The difference 

 between this environment and that of A. exulans is perceptible at once. 

 The latter is confined to the summits of high mountains, or to high 

 latitudes, where the stress of the organic environment is reduced to a 

 minimum. The environment of the former extends from sea-level to 

 7,000 ft. or 8,000 ft., and the insect is subjected to an organic environ- 

 ment differing as greatly as the fauna and flora of Italy and Greece, 

 the west coasts of Great Britain and Scandinavia ; it is subjected to a 

 climatic environment differing as greatly as the hot plains of southern 

 Italy and Asia Minor, the wet west CQasts of Britain and the cold of 

 the highest Alps of Dauphine, Piedmont, Switzerland, Carinthia 

 and the Pamirs, where winter lasts for at least eight months in the 

 year. Under such varying conditions, local races differing in size, 

 scaling, and general appearance are produced, whilst a number of 

 separate forms — erythrxis, rubicundus, brizae, etc.— appear to have been 

 developed from this species along the shores of the Mediterranean, where 

 the stress of the organic environment is probably at its greatest. How 

 far are heringi, pluto, uubit/ena and polygalae distinct species ? Experts 

 have so considered them, and yet we are inclined to conclude that the 

 sum total of characters is insufficient to give them specific rank. Quite 

 recently Calberla has shown that the male genitalia of rubicundus are 

 fixed, and on this one character we are constrained to consider it a 

 species apart from •purpwalis, of which it had previously been con- 

 sidered a local race. So little is necessary to change the opinion of 

 lepidopterists as to whether an insect is a local race or distinct specie?. 



