HYDROPSYCH^DiE. . 167 



Family IV.— HYDROPSYCHIDtE, Curtis, 



Antennw in general very slender, sometimes very much attenuated and 

 elongate, at others stouter and not so long as the wings : maxillary palpi 

 similar in the sexes, 5-jointed, the terminal joint very long and filiform, 

 frequently longer than the four others united, the basal joint mostly short, 

 the two next of nearly equal length, and the fourth rather longer : wings 

 moderately broad, the anterior with very few, or no, transverse nervures, 

 the hinder margin either rounded or somewhat obliquely truncate ; posterior 

 wings ample, more or less folded towards the inner edge : abdomen longish 

 and rather stout, of the males with small horny lamellae at the apex, of the 

 females obtuse : legs moderate : tibice with a pair of spurs at the apex, the 

 anterior sometimes with a single additional one in the middle, the interme- 

 diate and posterior with a pair at or below the middle. 



Larva, as in the preceding family, with or without external respiratory organs, 

 not residing in a case; pupa inclosed in a single silken envelope, con- 

 structed of silk, with bits of plants and small stones intermixed, or merely 

 a simple cocoon. 



The insects of this family differ from those of the foregoing by- 

 having the terminal joint of the palpi remarkably long and slender, 

 and apparently divided into numerous rings or rudimentary joints ; 

 they are of dull hue in general, and many of them are so extremely 

 similar to each other that the utmost caution is requisite to separate 

 them : the respective genera, however, differ much in habit from 

 each other. 



This family may be thus divided into genera : — 



Tibiis anticis 3-calcaratis ; 



yl/«s arafim nervis transversalibus diversis: . . 14. Cyrnus. 



paucis ; 

 Antennis alls lou^onhus i . . .11. Plectrocnemia. 



haud longioribus ; . . 15. Polycentropus. 



Tibiis anticis 2-calcaratis ; 



Antennis gracilis alis longioribus ; 



u4& jBOsftm parvis, vix plicatis ; . 12. Philopotamus. 



amplicibus, valde plicatis ; 13. Hvdropsyche. 



brevibus alis brevioribus ; . • 16. Aphelocheira. 



