142 ERNEST A. BACK. 



CREATION OF NEW SPECIES. 

 It goes without saying that great care should be exercised 

 in the creation of new species. This is especially so in the 

 genera Deromyia, Stenopogon, and Cyrtopogon. There will 

 always be in any large collection of the genera specimens that 

 cannot be identified with any degree of certainty, either be- 

 cause of a limited amount of material or on account of poor 

 condition. For the proper identification both sexes in good 

 condition should be had and pains should be taken in collect- 

 ing to carefully label all species, and to keep the sexes together. 

 Descriptions of new species, based on a single or several 

 females, especially when in poor condition and belonging to 

 Stenopogon and Crytopogon, are an abomination to future work. 

 It would be far better to allow the material to wait until more 

 specimens are at hand, even if one has to forego the pleasure 

 of creating new species. Exceptions to this are found in forms 

 so striking from the standpoint of size, coloration or habitat 

 that they would be recognized easily in any collection. No 

 one should attempt to describe new species in these genera 

 without a good series of the already described species before 

 him. 



CHARACTERS OF THE ASILID^E. 



Predaceous species of moderate to large size, though some- 

 times very small, usually more or less elongated in form, in 

 some cases very hairy, almost always bristly, the bristles us- 

 ually conspicuously strong. Head flattened, usually broader 

 than high, though sometimes quite narrow and when so less 

 flattened, separated from the thorax by a freely movable 

 neck. Vertex usually distinctly depressed between the eyes, 

 in a few instances scarcely so; eyes in both sexes separated, 

 rarely nearly contiguous above; three ocelli present, situated 

 on a more or less rounded tubercle usually on the vertex. 

 Antennae porrect, simple, composed of three segments, the 

 third usually more or less elongate, sometimes shorter and 

 more oval, with or without a terminal style, the style some- 

 times thickened and forming one or two apparent antennal 

 segments. Proboscis never elongate, firm and horny, adapted 

 for piercing, directed forward or forward and downward; palpi 



