THE ALDER 77 



with the ventral side uppermost, in order to 

 show the characteristic deep orange-red colour 

 of the underside of the abdomen. The male is 

 an insignificant little fly, with long sprawling 

 legs and often, but not always, aborted wings. 

 r. nebulosa has not yet been reported on chalk- 

 streams. Another species, very plentiful in the Tamiop- 



. ~ . . teryxrisi. 



north, is T. nsi. 



Order . . Neuroptera 



Family . . SIALIM; 



Genus . . Sialis 



Species . . lutaria 



PLATE XVI 



Sialis lutaria is the alder of the fisherman, Sialis lutaria, 

 and occurs in abundance on the banks of almost 

 every trout-stream in this country. Its value 

 to the fisherman is probably due to the re- 

 semblance shown by his artificial pattern to the 

 Welshman's button or other caddis-flies, for the 

 alder itself is rarely found in the water, as it 

 deposits its eggs on the sedge, and the mature 

 fly emerges through the turf. 



A second species, Sialis fuliginosa, occurs in siaiis 

 this country, differing from S. lutaria in its fuliginosa - 

 darker colour (nearly black), and in the position 

 of a small nervure in the anterior wings. I 

 have taken this species on the banks of the 

 Tummel. 



