494 DIPTERA CHAP. 



The males are remarkable for the curious special characters they 

 possess on the feet, antennae, face, or wings. These characters 

 are not alike in any two species ; they are believed to be of the 

 nature of ornaments, and according to Professor Aldrich and others 

 are used as such in courtship. 1 This family of flies approaches 

 very closely to some of the Acalyptrate Muscidae in its char- 

 acters. It is united by Brauer with Empidae to form the tribe 

 Orthogenya. Although the species are so numerous and 

 abundant in Europe, little is known as to their metamorphoses. 

 Some of the larvae frequent trees, living under the bark or in 

 the overflowing sap, and are believed to be carnivorous ; they are 

 amphipneustic ; a cocoon is formed, and the pupa is remark- 

 able on account of the existence of two long horns, bearing the 

 spiracles, on the back of the thorax ; the seven pairs of abdominal 

 spiracles being excessively minute. 2 



Series 3. Cyclorrhapha Aschiza 



Fam. 28. Phoridae. Small flies, with very convex thorax, 

 small head, very small two-jointed antennae, bearing a long seta ; 

 femora more or less broad; wings with tivo dark, thick, approxi- 

 mate veins, meeting on the front margin near its middle, and 

 besides these, three or four very fine veins, that run to the margins 

 in a sub-parallel manner without forming any cells or forks. This 

 obscure family of flies is of small extent, but its members are ex- 

 tremely common in Europe and North 

 America, where they often occur in 

 numbers running on the windows of 

 houses. It is one of the most isolated 

 FIG. 236. Wing of Trineura groups of Diptera, and great difference 

 aterrima, one of the Phor- o f opinion prevails as to its classifica- 



idae. Britain. mi , T 



tion. Ihe wmg-iiervuration is peculiar 



(but varies somewhat in the species), the total absence of 

 any cross -veins even on the basal part of the wing being 

 remarkable. There are bristles on the head and thorax, but 

 they are not arranged in a regular manner. The larvae 

 live in a great variety of animal and vegetable decaying matter, 



1 Amer. Natural, xxviii. 1894, p. 35. 



2 Perris, Ann. Soc. ent. France (4) x. 1870, p. 321, pi. 4 ; and Laboulbene, op. 

 cit. (5) iii. 1873, p. 50, pi. v. 



