1145 
In Poecilostola punctata (fig. by Grinperc, Diptera, in Braver’s 
Siisswasserfauna Deutschlands, p. 57) a similar median row of small 
spots is seen between first and second anal nervure, thus giving 
ground for the supposition that here also a vein may have been 
Fig. 3. Poecilostola angustipennis, (VANSDER Wurp). 
Fig. 4. Poecilostola punctata, (Met). 
obliterated, viz. An,. But at the same time amongst the small spots, 
which are arranged in rows, we find a number of larger ones dis- 
tributed, some of them showing an irregular configuration, as if they 
had arisen by the coalescence of a certain number of smaller ones. 
These bigger spots lie in the first place at the end of the longitudinal 
veins, in the second place on forkings and junctions. 
Extending our comparison to Acyphona maculata (GRÜNBERG p. 29) 
we find here all the above mentioned bigger spots, arranged in the 
same way, while the smaller ones with a very few exceptions, are 
absent. This suggests the conclusion, that the absence of the small 
spots is caused by their obliteration. 
Further extending our investigations to forms with a reduced 
nervural system, e.g. members of the genera Tephritis, Sciomyza 
and Traginops, we see the same feature as in the Haematopotas, 
viz. regular alternation of light and dark patches, arranged in rows 
along the veins, but modified and complicated in so far as either 
