Biology of the Membra, cidae of the Cayuga Lake Basin 205 



Buckton (1903:204) has suggested that previous to the glacial period, 

 when " the monkey and the palm-tree occurred within the limits of the 

 Arctic Circle," the Membracidae may have become distributed by a 

 northern route. This theory can be attacked, of course, from a number 

 of angles, but such criticism is here unnecessary'. 



The older authors were unanimous in treating the IMembracidae from 

 a strictly geographical viewpoint. Thus, Stal considered separately the 

 membracids of Africa, Mexico, South America, and the Philippine Islands, 

 and established for each geographical area new genera and species, with 

 separate keys and tables for each. The result of such work has been a 

 useless accumulation of synonyms and an incorrect idea of the definiteness 

 of geographical barriers. 



It is now known that the same genera, and in a few cases the same species, 

 of Membracidae may occur in widely separated continents. The forms 

 of Asia merge gradually into those of the Philippines, and these in turn 

 into those of the East Indies and Australia. The South American forms 

 are closely related to those of Africa, while the Palearctic and Nearctic 

 forms are entirely distinct. 



It seems more reasonable, therefore, to presume that the IMembracidae 

 originated as tropical forms; that the first migration was eastward and 

 westward in equatorial regions; and that later the forms migrated north- 

 ward and southward on the respective land-masses of the eastern and 

 the western hemisphere, their limits of distribution depending on the 

 adaptability of the species to environmental, and particularly to climatic 

 and floristic, conditions. Records of distribution from all parts of the 

 world bear out such an hypothesis to a large extent, and the geological 

 theories of land bridges and life zones in comparatively recent times, as 

 used to explain the appearance particularly of birds and mammals, are 

 sufficient to account for earlier tropical migrations. 



As considered in regard to the modern geographical areas as life zones, 

 the Membracidae are represented as follows: 



Palearctic region 



(Europe, the temperate parts of Asia, and the north of Africa; Iceland and the islands of 

 the Atlantic; limited by the Himalayas) 



v'ery poorly represented. Only two or three genera on the entire continent of Europe, 

 but two species in Great Britain, two species in Russia, and none reported from Iceland. A 

 few in northern Africa, chiefly forms that have migrated from the South. 



