60 



THE NORTH AMERICAN SPECIES OF DROSOPHILA. 



students. In general, the opinion of the most recent student has been 

 accepted in matters of synonymy and generic references. 



Table 8. 



* Includes Australia and New Zealand. 



This list, of course, is an index of the thoroughness with which the various 

 regions have been studied, as well as of the number of species actually 

 occurring in them. The total of 202 species is certainly far too small. 

 Perkins (Fauna Haw., 1, clxxxix) says not less than 250 species of the tribe 

 must occur in the Hawaiian Islands alone, and most of these forms appar- 

 ently belong to the genus Drosophila itself. All the regions except the 

 Palsearctic and Nearctic will certainly yield very many more species when 

 they are thoroughly collected, and the two regions named are by no means 

 exhausted of new species. 



The distribution of the genus within each region is not adequately known, 

 but it seems probable that Drosophila is to be found everywhere except in 

 very cold regions. The data on the point that I have collected from the 

 literature and from my own observation of specimens follow : 



Palsearctic: Faroe and Canary Islands to Sweden, Egypt, Chinese Turkestan, and Japan* 



Ethiopian: Eritrea to Ashantee, Rhodesia, Mauritius, and the Seychelles. 



Oriental: New Zealand to the Phihppines, Java, and India. 



Nearctic: Nova Scotia to British Columbia, southern Cahfornia, and Florida, Bermuda. 



Neotropical: Florida, Bahamas, and Cuba to Argentina, Chile, and Mexico. 



Polynesian: Tahiti, Hawaii, Fiji. 



D. remota Walker was described from the island of Tristan d'Acunha; 

 but, like most of Walker's species, this can not be accepted until verified. 



There are not very many species of Drosophila common to the nearctic 

 and Neotropical regions (only eight). In addition, three Neotropical species 

 occur in southern Florida, where Nearctic species are also to be found. 

 Since a number of the Neotropical species are imperfectly known, it is 

 difficult to place them conveniently in a key. Accordingly two keys have 

 been constructed. The first, which is only slightly modified from the one 

 already published (Bull. Amer. Mus. Nat. Hist., 38, 443), includes the known 

 Nearctic species, and the three Neotropical forms found in southern Florida 

 (D. lutzii, D. willistoni, and D. cardini). The second key includes the 

 Neotropical forms known from the West Indies (including Trinidad) and from 

 Central America (including Panama) and Mexico. 



