584 



Dr. D. Keilin on the 



1. Dasyhelea flavifrons, Gueriii, 1833. 



This midge was bred by Guerin from pupae found in the 

 decomposed sap of an elm tree (in Paris). In liis paper he 

 gives a figure of the pupa (pi. viii. fig. 2, e), which unfortu- 

 nately does not convey a single character of taxonomic 

 importance. 



The same species was also bred by Dr. Sharp from beech- 

 tree sap in the New Forest, and by F. W. Edwards from 

 horse-chestnut tree sap at Sidmouth. Through the kindness 

 of Mr. F. W. Edwards, I was able to examine a few larvae 

 and pupae of this species, and to compare them with those 

 of D. obscura, Winnertz. The character of the larva of 



Text-fis'. 4. 



Dasyheha fiavifrons : A, rectal gills ; B, respiratory prothoracic horns. 



D. fuvlfrons which enables one to differentiate it most 

 readily from D. obscura is in the structure of its rectal 

 gills. As text-fig. 4, A, shows, the 8 terminal branches in 

 D. fiavifrons are much longer than those in D. obscura [cf. 

 PI. XX. fig. 14). The prothoracic horns of the pupa in 

 D. jiavifrons (text-fig. 4, B) each bear only 13 spiracular 

 papill;i3 instead of 21-22, as is the case in D, obscura. 



2. Dasylielea clufouri, Laboulbene, 1869. 



The larvae and pupae of this species were discovered by 

 Laboulbene (1869) in the thick sap filling the wounds of 

 elm trees in Paris : his descriptions of larva and pupa are, 

 however, very incomplete, and do not contain any characters 

 of use in the identification of this species. 



