RHYACOPHILID.E. RHYACOPHILA. 165 



testaceous, densely clothed with golden hairs, immaculate ; cilia slightly 

 fuscescent, posterior somewhat more transparent and slightly iridescent ; 

 legs ochreous-yellow ; antennae ochreous, annulated with fuscous. 

 Taken within the metropoUtan district, in June. 



Genus X.— RHYACOPHILA, Pictet. 



AntenncE rather slender, not so long as the wings, placed somewhat remotely, 

 the basal joint stoutish: maxillary joa/^j rather long, slender, nearly glabrous, 

 a little porrected obliquely: head smallish, and rounded, hairy in front: 

 eyes rather prominent, lateral: wings long, and somewhat elliptic-acute; 

 anterior with three elongate discoidal areolets, from the first of which arise 

 four sub-simple nervures, running parallel with the stigma, then follow two 

 bifid ones, and on the anal angle are two simple ones, which arise from the 

 apex of the inner areolet ; posterior wings shorter, small, also with three 

 elongate-discoidal areolets, and with one of the nervures very distinctly 

 furcate near the margin : abdomen longish, compressed, attenuated to the 

 apex ; of the males furnished with long horny appendages, the two inter- 

 mediate being laminated and bifid, the two others spiniform, the larvae are 

 bifurcate : legs rather slender ; anterior pair shortest : tibice all armed with 

 a pair of long spurs at the apex, the anterior with one also below the 

 middle, the intermediate and hinder pair each with a pair near the apex. 

 Larva with external respiratory organs, the segments somewhat remote, 

 rounded on the sides, the terminal one with a bifid appendage at each side. 

 The three-spined anterior tibias of the insects of this genus, form a 

 conspicuous mark of distinction from those of the other genera of this 

 family, and their palpi remove them from the Hydropsychidae, in 

 which family several genera are characterized by having a spur on the 

 side of the anterior tibias: the larvae of the Rhyacophilidae have their 

 respiratory organs external. 



A. Body slender: (intermediate tibias and tarsi of the females not dilated). 



Sp. 1. vulgaris. Fusco-ochracea, alis hyalinis, anticisfusco subpunciatis, macu- 

 lacjue dorsali communi rhomboidali pallide-Jlavescente. (Long. corp. 5—6 lin.; 

 Exp. Alar. 1 unc. 12—13 lin.) 



Phi. obsoletus. Steph. Catal. 318. iVo. 3604. — Rh. vulgaris. Pictet, p. 182. 

 pi. XV. f. 1. — Phi. dorsalis. Phil. Mag. (Curtis) v. iv. p. 213.^ 



Head, antennae, and body ochreous-brown, spotless ; eyes black ; anterior 

 wings hyaline, pale dull ochreous-brown, with minute darker punctures in 

 the direction of the nervures, especially towards the inner and hinder 

 margins, and an irregular, somewhat triangular, spot in the middle of the 

 inner edge, forming, with the opposite wing, when closed, a rhomboid spot; 

 the posterior wings are more transparent, faintly iridescent, and spotless ; 

 legs pale ochreous. 



