L147 
mental condition exists, while the deviations must be explained 
either by coalescence of dark spots to larger coloured areas, or on 
the contrary by reduction of the pigmented parts, bringing the light 
areas into predominance. Also in these animals the proximal half 
of the wing generally is the less -coloured, showing fewer and 
smaller spots, resulting in their total absence in the departments 
of lobus and alula. 
Turning to those cells, which contain either a dark or a light 
median streak, these are seen to be precisely those which may be 
supposed to have been formed by coalescence of two neighbouring 
internervural areas, by the obliteration of the nervure originally 
separating them. In Sciomyza javana, which shows these dark 
median bars to perfection, they stretch along the spaces, which in 
Diptera with a more complete nervural system are occupied by the 
fourth radial and the first median vein. We therefore are justified 
in assuming, that we have here the same phenomenon which is seen 
in Lepidoptera-wings (esp. Papilionids and Danaids), where the 
course of obliterated veins in the discoidal and cubito-anal cells is 
marked either by black or by light streaks of pigment. 
De Meyer also has given his attention to the pigmentation of 
the median streaks in internervural cells, for he says on p. 58: !) 
In the cells of Diptera-wings median rows of spots occur relatively 
seldom in typical array. As examples may be given: Sciomyza 
Schönherri, Hydrophorus nebulosus (between the 1st and 2»¢ and the 
2d and 3rd longitudinal vein respectively, while pigmentation of the 
end of the nervures, seams of colour along transverse veins, and 
traces of a double row of spots in the upper part of the middle of 
the hindmarginal cell also occur), Ilythea spilota, Scatella quadrata, 
furthermore some Pteroeallines. In several species related to the 
first mentioned ones especially among Tetanocerinae, the median 
spots are well marked in the hindmarginal cell, a double row of 
spots occurring in the remaining longitudinal cells. As in Schönherr! 
the spots often already appear as transverse streaks, and as in other 
cases there is an evident connection between two spots lying one 
above the other in the same cell, as indicated by their position, 
it is my opinion, that such a double row of spots must be considered 
as resulting from the division of a median row. I may cite a 
typical example in Tetanocera (Pherbina) punctata, which at the 
same time shows a further feature, viz. a median longitudinal streak 
in the cells’. 
1) Translated from the German original by me. 
