24 Records of the Iiiaian Museum. [\/Oh. X, 



the inferior nature of the character (Monog. iv, 15) and considered 

 Coquillett wrong in upholding their importance. He says {I.e. iv, 

 122), " unless both sexes are seen, it is quite impossible to place 

 any culicid in any of the sections into which the family is 

 divided." 



I am not yet disposed to admit any high value to this charac- 

 ter unless there is good evidence that practically all individuals 

 can be definitely allotted to one or other of the alleged subdivi- 

 sions; and in other works I have ventured to question the 

 supposed high taxonomic value of what is perhaps a somewhat 

 analogous character, the presence or absence of small (often very 

 minute) spines at the tips of the tibiae in Tipulidae, to which 

 much importance is attached by some authors. Mr. Edwards 

 however finds sufficient reliability in the claws to use them as 

 of primary importance in differentiating genera, but this method 

 places Stegomyia in the Aedes group which does not seem to me 

 its natural afhnity. Besides, a character dependent on the female 

 sex alone is nearly always a doubtful one. 



The Ventation. — There are several families amongst the 

 diptera of which each family possesses a type of venation entirely 

 peculiar to itself. 



In addition to those with practically but a single genus each, 

 Rhyphidae, Dixidae, Simuliidac , and Orphiiephilidae; the Leptidae 

 (with the Tahanidae), the Stratiomyidae , and Syrphidae, also the 

 Tachininae and Anthomyinae subfamilies of Muscidae} all possess 

 strikingly specialized types of venation, each peculiar to one family 

 only. The Culicidae undoubtedly form another family of the same 

 category, offering as pronounced an example of uniformity of 

 venation as can be found. The Psychodid wing is closely allied 

 but differs fundamentally in the basal proximity of the cross veins. 



On the other hand, in Tipulidae, Mycetophilidae, Chirono- 

 midae, Bomhylidae, Cyrtidae, Empidae and others we find exten- 

 sive modifications of the type venation peculiar to each. 



Genera founded on the presence or absence of certain veins or 

 cells are ordinarily quite valid and constant, but exceptions are 

 not rare, and individual aberration has to be allowed for. In 

 Culicidae the genera varying most would appear to be Megarhinus, 

 Miicidus, Uranotaenia , and Culex. 



Exact precision cannot be expected, and in the matter of 

 venation a little wider range of individual variation must be 

 allowed for, even to the two wings of an individual specimen, such 

 instances being not at all infrequent in many families. This 

 margin of individual variation is known to every depterologist. 

 The venation has, however, been largely ignored by culicid writers 



' It may be noted that in the Muscidae, sensu latisstmo, I recognise but a 

 single family, with the Tachininae (including the Dexids and Sarcophagids). 

 Muscinae and A nthomyiuae as three subfamilies ; each of the Acalyptrate groups 

 ranking also as subfamilies of equal rank with these three. The Acalyptrata as a 

 group possess technically the same type of venation as the Anthomyinae, but modi- 

 fied forms are found, each more or less peculiar to one subfamily only. 



