594 DERMATINA 



quently the upper basal cell twice as long as tlie second one unless tlie second one 

 is lengthened ; anal cell closed well before the wingmargin through the sharp 

 descent of the lower branch of the postical fork. Wing membrane smooth, never 

 ribbed, but minutely pubescent. Squamee (alar) small but fairly well developed 

 and bearing very short fringes ; thoracal squamae almost absent. Halteres in no 

 way concealed, knob large. 



The metamorphoses are well known, and the larvae (which are closely 

 allied to those of the Therevidce) have an obvious head and are amphi- 

 pneustic, while the pupae are mummiform. The species used to be 

 called " Carpet Flies " and the larvae were accused of destroying carpets 

 and more especially stable rugs, &c., but from their afifinities it is now 

 believed that they prey upon the larvae of Fleas (Pulex) and Clothes Moths 

 (Tinea) which occur in the rugs and that they are consequently bene- 

 factors. In some ways the larvae are said to show tendencies towards 

 those of Nemotdus and Pachygaster. The flies are not common in the 

 perfect state but sometimes occur on windows, especially in stables and 

 outbuildings. 



The Scenopinidm form a very small but very distinct family, which is 

 easily recognised by the eremochaetous (in fact absolutely naked) body, 

 there being no true pubescence on the head, thorax, or abdomen ; 

 they are distinguished from the true Eremoch^ta by the absence of any 

 middle pulvillus or pulvilliform empodium. Girschner says that in the 

 structure of the abdomen, the nature of the wing-membrane (which 

 is smooth), and the legs, as well as in " habit," they bear closer relation- 

 ship to Subula {Xylomyia), and especially to the Xylojpliagidm, than to the 

 Therevidce. In fact the Scenopinidce show so many characters indicating 

 most diverse affinities that great uncertainty has prevailed as to their 

 proper position, but a steadily growing knowledge of the life history has 

 placed them beyond doubt in close relationship to the Tlicrevidce, in fact 

 so close that Osten Sacken joined them at one time with that family, 

 though how he could have associated them with his aerial furry-haired 

 Tkomopteea seems sti'ange. Brauer in his latest arrangement associated 

 them upon larval characters with the Therevidm in his section " Polytoma," 

 though only just previously (1882) he had devoted nearly eleven quarto 

 pages to the question of their proper location and had decided to 

 place them as intermediate between the Therevidce and Mydaidce., though 

 with the more close affinity to the latter. Different though they are at 

 first glance from the Mydaidce, I have found that close examination tends 

 to bring them into intimate connection, and I do not think that I am 

 wrong in uniting them with the Mydaidce in a super-family (Dermatina) 

 of practically equal rank with the Tromoptera or Energopoda. The 

 usually complete absence of pubescence and the frequent three posterior 

 cells will distinguish them at a glance from the Therevidce, while the 

 simple venation will at once distinguish them from the Mydaidce. The 

 absence of an ambient vein is shared with the Stratioinyidce and some 

 Cyrtidce, but I do not believe that it shows any affinity. A strong 



