36 INTRODUCIION. 



magnitude, if other families, as may reasonably be supposed, are 

 as prolific of new forms as the Culicid.i; have proved. 



tScliiuer in 1868,* in noting that 19,449 species were at that 

 time known, distributed them geographically as follows : — Europe 

 8670, Asia 2046, Africa 1644, America 5577, and Australasia 

 1056, the remaining 516 coming from unknown localities. In 

 Hardwicke's ' Science Gossip,' fifteen or more years ago, cal- 

 culating 2^'>^^ ''"^^ according to geograpical areas, I estimated 

 200,000 as a quite moderate estimate of the number of species in 

 actual existence ! 



The Paloearctic Catalogue, recently issued, gives a little over 

 13,000 t as inhabiting the Palaearctic Eegion up to the year 1907 ; 

 Aldrich accumulates about 9000 species indigenous to North 

 America J; Van der Wulp's Catalogue of 8outh Asian Diptera 

 totalled 2889 up to not later than 1906 ; whilst a manuscript 

 Catalogue of my own compiled on the recorded Australasian 

 Diptera includes about 2000 (up to 1909), to which I am 

 continually making additions that have been overlooked. 



The gigantic Catalogue of the world's Diptera, by Prof. Kertcsz, 

 now in progress, gives a total of about 13,600 species as known iu 

 the families at present dealt with ; that is to say, the Nematoceea 

 and practically all the remaining families except the Muscidj 

 If this last enormous family bears the .same ])roportion iu the 

 world's species as it does in the Palaearctic fauna, it should 

 comprise 14,000, making a total of between 33,000 and 34,000 as 

 actually known from all parts of tlie world. 



But since the publication of the two volumes containing the 

 Nematooeba, something like 500 species of Culicid^ alone liave 

 been described, whilst my own labours in this suborder will 

 result in the erection of considerably over 300 more (including 

 those in this volume), without touching the Culicid.tj, Chirono- 

 Min.E and Cecidomyid^^, and these 300, moreover, are from the 

 Orient alone. Prof. Ivieffer has added about 250 species to, the 

 Chironomid^ and a limited number to the CECinoMyin.E, all 

 these practically from the Indian Empire only. 



To illustrate how small a region has been worked over, ic may be 

 noted that the Oriental Nematocera were represented by only 

 230 species in Van der AV^ulp's Catalogue (1896), since which the 

 number has been increased to 1200 or a gain of over 400 ^'1^. 

 Moreover, even this great increase of species has been gleaned from 

 a comparatively small number of localities, the bulk of them (with 

 the exception of the CuLiciDyi;) having been collected in three or 

 four Himalayan districts of quite limited extent (Mussoori, Simla, 

 Naini Tal and Darjiling) ; Calcutta and its immediate environs ; 



* "Eeise der Novara." 



t This is an approximation : tlie actual number of species contained in each 

 of the four volumes noi being quoted by the authoi-s, but the estimate is 

 probably sufficiently near the truth for the present purpose. 



I " Catal. North Amer. Dipt." (1905). The esiinuiteismine ; the catalogue 

 is compiled up to Jan. 1st, ll)04. 



