29 



posterior wiugs, uot ending in a forked cell. It is a pretty, sharply- 

 marked insect. Perhaps Plectrocnemia liturata, of Kolenati, belongs 

 here. Polycentropus picicornis, of Ilagen, is different. 



CYENUS — Stephens. 

 Although this genus was merged into the preceding, it seems to 

 me advisable to restore it for the reception of those species in which 

 the first apical sector (anterior branch of the ramus discuidalis) in the 

 anterior wings is simple, and thus, as is truly remarked by Stephens, 

 there are only four apical forks. Besides, the posterior wings are much 

 narrower, the anal portion not dilated, and the anterior branch of the 

 ramus discoidalis in these wings is not clearly separable from the radius, 

 except, perhaps, at the extremity. I distinguish two British species, of 

 which one is apparently undescribed. 



Oyrnus trimaculatus — Curtis. 

 Fhilopotamus trimaculatus, Curtis Phil. Mag. 1834, p. 213; Poly- 

 cenlropus trimaculatus, Hag. Ent. Ann. 1861, p. 4, 91; Ci/rnus 

 pulchellus, Steph. 111. p. 175, 2 (1836); G. unipunctatus, Ste^h. 

 111. p. 175, 1 (1836), worn. 

 A common species about some of the canals and slowly flowing 

 rivers near London, and probably widely distributed. The upper edge 

 of the discoidal cell in anterior wings is sharply angulated at the point 

 where a transverse vein connects it with the radius. The anterior wings 

 are pale fuscous, thickly sprinkled with pale yellow spots, some of which, 

 on the dorsal margin, are larger than the others. In the male the app. 

 sup. are very small and rounded; app. intermed. rather long, pointed, 

 straight; app. inf. large, almost truncated at the extremity. 



In Stephens' collection under O. pulchellus are four of this species 

 and one of Polycentropus picicornis. 



Gyrnus flavidus — new species. 

 The only locality that I know with certainty to produce this species 

 is the remnant of the Croydon canal at Forest Hill, Kent, where it is 

 not very uncommon in May and June. The anterior wings are longer 

 than in the last species, and the discoidal cell is not sensibly angulated 

 at the point where the transverse vein uniting it to the radius is placed. 

 The wings are very pale yellow, reticulated with grey. The app. 

 intermed. are apparently wanting; the app. inf. are more rounded than 

 in the last species. I reserve a detailed description for another 

 opportunity.* 



* Tliis is closely allied to Philopotamus urbanus, Rinibur, but after a careful comparison with the 

 type, Dr. Hagen considers them distinct, and gives numerous reasons for arriving at that conclusion. 

 Want of space prevents me from going into details here. 



