27 



POLTCENTROPua — Curtis. 



This genus, as restricted by me, may be yet further divided accord- 

 ing; to the neuration. I can speak with certainty of only four British 

 species. 



a. — In the posterior wings the anterior branch of ramus discoidaUs 

 forms a forked cell at the apes, and the discoidal cell is open. 

 — P . flavomaculatus and P. multiguUatus. 

 h. — Anterior branch of ramus discoidaUs in posterior winga 

 simple, the discoidal cell closed. — P. suhnebulosus and P. 

 picicornis. 



Polycentropus flavomaculatus — Pictet. 

 Hydropsyclie flavomaculatus, Pict. Eecherch, p. 220, 29, pi. 19, fig. 



2 (1834) ; Polycentro'pus irroratus, Curt. Brit. Ent. pi. 554 



(1835) ; Steph. 111. p. 178, 7; Hag. Ent. Ann. 1861, p. 3, 88; 



P. pyrrhoceras, Steph. 111. p. 177, 3 (1836), not of Hagen; P. 



fuliginosus, Steph. 111. p. 177, 4 (1836) ; P. concinnus, Stepli. 



111. p. 178, 5, (1836) not of Hagen ; P. trimaculatus, Steph. 



111. p. 178, 6, not of Curtis or Hagen; P. subpunctatus, Steph. 



111. p. 177, 1 (1836), partim. 

 This is the most common species of the genus, according to my 

 experience, and seems to be generally distributed, preferring running 

 •waters, but also sometimes frequenting canals, &c. This and the next 

 may be readily distinguished by the open discoidal cell of the hind wings, 

 and also by another very constant character in the neuration, viz. ; that 

 the two first of the simple veins traversing the anal portion of the wing 

 (termed costulw by Kolenati) are connected at about the middle by a 

 small transverse vein. These, I think, are the only instances in the 

 British Triclioptera in which these two veins are united in that manner. 

 The anal appendices are well developed. In P. flavomaculatus, from the 

 middle of the upper margin of the last abdominal segment, thei'e pro- 

 ceeds a broad membranous lobe, capable of considerable lateral extension 

 by the living insect, but which is very liable to change form in drying ; 

 from under this lobe proceed the appendices intermed., which are 

 strongly divergent and somewhat curved ; app. sup. rather large, flat, 

 obtusely rounded; app. inf. similar in form to the app. sup., lying close 

 together on the ventral surface. 



Polycentropus multiguttatus — (Curtis) Hag. 

 Polycentropus multiguttatus, Curt. Brit. Ent. p. 544 (1835) ? ; Hag. 

 Ent. Ann. 1861 p. 4, 89 ; Plectrocnemia atomaria, Kol. gen, at. spec. 

 Trichop, pt. 2, p. 212, pi. 1, fig. 10—11 (1859). 



