igio.] E. Brunetti : Taxonomic values in CidicidcB. 57 



the statements made by the latter author concerning the Hfe history 

 of various CuHcidae as compared with species of Chironomida^, 

 Psychodidse and Dixa. As I am personally unacquainted with the 

 earlier stages of any of these genera, it would be presumption to 

 decide " when doctors disagree/' but I have seen no reply to Mr. 

 Knab on the subject, and his facts appear well founded. 



Regarding Dixa, it has always been regarded as somewhat 

 abnormal ; to me personally it appears intermediate between 

 Tipulida^ and Culicida?. 



The excuse for the erection of such a number of new genera, 

 and the splitting up of the CuHcidae into several sub-families, is 

 usually the unwieldiness of the genera, which otherwise would 

 contain such a large number of species in each. 



As it is well known to be a common thing for students to deter- 

 mine the species first, and discover its genus afterwards, the in- 

 stability of most of the genera is surely' emphasized, as the present 

 writer never heard of this method of determination being followed 

 in any other group. 



Moreover it is entirely wrong, scientifically, to consider that 

 the presence of a large number of species in any genus is sufficient 

 justification for dividing it into several others and according them 

 equal value. A genus, as Prof. Williston truthfully sa^'s, should 

 be something more than a second name for a species, or a cogno- 

 men established for convenience' sake only. ' ' A genus is a concept ' ' 

 is written in the late Baron Osten Sacken's handwriting, inside 

 the covers of his hand-cop}' of Aldrich ' s Catalogue of North American 

 Diptera (now in the possession of the Indian Museum), and it should 

 have a real zoological value and significance ; all genera throughout 

 the animal kingdom being theoretically more or less on the same 

 plane of systematic value. Personally, I object to all classification 

 which is not as nearly as possible a natural one, and purely artificial 

 groups should at the very outside attain only the rank of sul)- 

 genera.^ 



The plea of the unwieldiness of extensive genera cannot be 

 upheld, as the sj-stematist is quite accustomed to such genera. 

 In the first five volumes of the Catalogue of Diptera now in process 

 of publication by Prof. Kertesz, are to be found numerous such 

 genera, with approximately the following number of species each : 

 Mycdophila 190, Sciara 460, Chironomus 320, Ciilex 182 (up to 1920), 

 Cccidomyia 180, Dasyiieura 160, Tipula 310, Odontomyia 160, 

 Chrysops 150, Pangonia 180, Anthrax 460, Exoprosopa 23P, Bomby- 

 liiis 240, Asilus 260, Promachus 150, Laphria 230, in addition to 

 nearly twenty others with a little over or a little under 100 species 

 in each ; the whole triumphantly capped b>- the gigantic genus 



' An objection to " preliminary descriptions," often of a few lines or words 

 only, may suitably be here recorded. It seems doubtful whether priority can 

 justly be claimed in such cases, the full descriptions being often long delayed ; 

 though I recognise the awkwardness of the situation in deciding whether a " pre- 

 liminary " description is of sufficient length to stand good or not. 



