COLLFXTING FTJES IN NORTHERN EUROPE 



By J. M. ALDRICH, 



.Issotlalc Cunilor. Division of fnsccis, IJ. S. National Miiscitiii 



Since the land masses of the Old and New \\'orlds come close 

 together at Pjering Strait, and did in fact once connect there ; and 

 since the climatic conditions are on the whole very similar in the 

 northern part of both hemisjiheres, it is not surprising that the animals 

 should have a marked similarity in North America and Eurasia in the 

 northern regions. A long list could be made of cases where the same 

 species of plant or animal occurs in both continents, as determined by 

 examining specimens from both ; but lack of material for comparison, 

 especially in the smaller forms, leaves a great deal of uncertainty as to 

 the identity. It was to provide such material in as many cases as pos- 

 sible that I undertook in the j^ast summer to carry out the project here 

 descri])ed. The investigation of the problem through the numerous 

 species of flies promises more interesting results than would be ob- 

 tained in other orders of insects, for the simple reason that the flies 

 are so plentiful in the north, having their region of greatest abundance 

 approximately between 50 and 60 degrees north latitude ; while all the 

 other large orders dwindle greatly in that cold climate and have their 

 greatest numbers farther south. Many American species of flies have 

 been described without the proper examination of related Old World 

 forms, and in some cases they will no doubt l)e found to be identical 

 with the latter. The jM'olilem will not be com])letely solved for many 

 years, but even a small collection of a few thousand Old World speci- 

 mens will afford opportunity to make a little jirogress in it. Hence 

 my object was to obtain as many flies as possible in the time available. 



Before beginning this work, however. I spent considerable time in 

 the examination of the type specimens of American flies in the British 

 Museum and in the important ]irivate collection of Mr. J. E. Collin 

 at Newmarket. England ; and after my collecting trip was finished I 

 returned by way of Stockholm, Copenhagen, and Paris, where muse- 

 ums long established contain additional type material of importance. 



I reached Bergen, Norway, by boat from Newcastle, England, on 

 July 10. As I did not leave on the northward journey until evening 

 of the following day, a little time was available for collecting flies here. 

 Taking the funicular railway to its terminus a thousand feet above the 

 sea on the stony mountain against which the town is built, I walked 



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