SYNOPSIS OF THE BRITISH PHRYGANID^. 99 



Sub-Family III. Sericostomides. 



Maxillary palpi of the males two or three-jointed, strongly 

 hairy, broadly curved upwards; maxillary palpi of the fe- 

 males five-jointed, with the basal joints thick, hairy ; ocelli 

 wanting ; spurs variable in number (2, 2, 4 ; 2, 4, 4 ; 2, 3, 3 ; 

 2, 2, 2) ; the anterior leg always with two spurs ; an- 

 tennae usually as long as the wings, strong, the first joint 

 thicker and usually long, hairy ; wings densely and strongly 

 hairy ; legs almost destitute of spines. 



Cases constructed of sand, swimming freely; the larvae 

 probably always live in running water of no great depth. 



The Sericostomides, by the remarkable variety in their 

 structure, constitute the chamber of curiosities amongst the 

 PlwyganidcB, as in almost every great family of insects 

 nature has selected one group in which to develope her 

 wealth of forms. 



Genus Sericostoma, Latreille ; Stephens. 

 Potamaria, Leach. 



Maxillary palpi of the males large, spoon-shaped, closing 

 together and thus covering the face with a mask, which is 

 clothed externally with distant, and internally with long, 

 curved, closely approximated hairs ; labial palpi of the males 

 with a long basal joint ; antennas strong, not so long as the 

 wings, the first joint thick, shorter than the head ; wings 

 densely clothed with hairs, narrow, the anterior with an 

 elliptical apex ; the posterior of equal breadth, but con- 

 siderably shorter; spurs 2, 2, 4; tibiae without spines. 



Case constructed of flue sand, conical, with the tail-end 

 slightly curved. The larvae live in rapid brooks. 



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