importation or no7i-importation of Diptera. 495 



This version is at any rate more probable than another 

 which I read in the German periodical, * Die Natm* ' 

 (1857, p. 282), that gnats were intentionally imported 

 into those islands by a mischievous sea-captain, in 

 vengeance against the inhabitants ! 



However, as the genus Culex seems to be cosmopolitan, 

 it is very probable that native species existed on some of 

 the islands of the Pacific Ocean. I read in F. D. Ben- 

 net's ' Narrative of a Whaling Voyage round the Globe 

 from the Years 1833 to 1836 ' (London, 1840) that on 

 Raiatea, one of the Society Islands, he met with a grey 

 Cidex, handsomely spotted with black, which was very 

 common and annoying in the jungle, but seldom appeared 

 in the villages. On Pitcairn Island the same traveller 

 was told that the mosquito {Culex) had been but recently 

 introduced. 



5. — Syephus pyrastei. 



The geographical distribution of this common species 

 offers some peculiarities which deserve to be noticed. It 

 is common throughout Europe, but not as far north as 

 Lapland ; it occurs in Egypt, Algiers, on the Canary 

 Islands, and Madeira (Schiner, I. c, and Macquart) ; 

 eastwards it has been found in Moscow (Fedtchenko), 

 Kharkow (Jaroscheffski), and in the Volga-Ural region 

 (Eversmann). Its occurrence farther east is very pro- 

 bable, but data are wanting. The S. lunatus, Wiede- 

 mann, from China, which this author calls "the 

 representative of the European S. pyrastri, only a little 

 smaller," may perhaps be the same species. 



A species which I cannot distinguish from aS. pyrastri 

 is quite common in the region between the State of 

 Colorado and the Pacific Ocean, including California. 

 Say discovered it as early as 1820 on the Arkansas 

 River, near the Rocky Mountains — at a time, therefore, 

 when that region was as distant from the centres of 

 civilisation as some places in the interior of Africa are 

 at present. He was aware of its resemblance to the 

 European species, and for this reason called it S.afjinis; 

 the difference which he notices, " a somewhat darker 

 colour," is unimportant. 



W^e thus have in the occurrence of S. 2W^^i^''^ oi^ the 

 western side of the American Continent a clear case of a 

 disconnected area of distribution. Remarkable as this is, 

 it is still more remarkable that the occurrence of S. 



