BY FREDERICK A. A. SKUSE. 661 



the position of the tip of the second longitudinal and the tip of 

 the lower branch of the fork of the third longitudinal vein, which 

 with rare exceptions are found constant in each species.* 



In the ultimate sei)aration of species, characters were found 

 in the length of the costal vein beyond the tip of the second 

 longitudinal vein, as compared with the distance between the tip of 

 the former and that of the anterior bi'anch of the third longitiidinal 

 fork ; also that the relative distances between the tip of the 

 posterior branch of the third longitudinal fork and the tip of 

 the anterior branch of the fourth longitudinal fork, and this latter 

 from the tip of its posterior branch, were valuable to notice. 

 Besides the consideration of the alar-vein system, Winnertz also 

 has shown that the relative lengths of joints of the legs are 

 important in specific distinction. 



With reference to the two main divisions of Sciara, Winnertz 

 adds a note of which the following is a translation ; — " In some 

 species the tip of the sub-costal (first longitudinal) vein joins the 

 costa opposite or beyond the root of the fork in the 5 ^i^d in 

 front in the (J ; in a few species its position, as well also that of 

 the cross-vein, is not at all constant. In these cases the respec- 

 tive species are mentioned according to their deviation in the 

 corresponding division, but they are described in that division to 

 which they belong according to their majority.'" 



Winnertz (Mon. der Sciarinen, p. 10), after characterising the 

 family Sciarida; draws attention to the close affinity of this 

 group with the Mycetophilidse, but at the same time gives the 

 following diagnosis of the characters which supply efiective 

 points of distinction, and he justly concludes that these devia- 

 tions give the Sciaridse a type so difi^erent from that of the 

 Mycetophilidse, that a combination of the two grou})S must 

 appear inadmissible. 



* Winnertz adds, "the position of the tips is determined by drawing a 

 straight line from the middle of the base of the wing through the apex, 

 upon which, as the foundation, perpendicular lines are drawn from the 

 respective points." 



