234 THE ENTOMOLOaiST. 



does not name, a form found on C. geoffroyi (as striata) ,* but 

 his note is of little value. 



Six genera of Corixidae are British, and may be separated as 

 follows : — 



Males. 



1. Minute species ; scutellum covered by pronotum only 



at anterior margin; face convex ; [strigil present] 



(1) MicRONECTA, Kirkaldy. 



1 a. Larger species ; face excavated ; scutellum more or 

 less membranous, concealed, except at posterior 

 angle, by the pronotum ..... 2. 



2. Strigil present ....... 4. 



2a. Strigil absent 3. 



3. No stridular area ; posterior tarsus not marked with 



black . .' (2) Cymatia, Flor. 



3fl. Stridular area present ; posterior tarsus marked con- 

 spicuously with black [the tarsal segment itself, 

 not the hairs only] . . . • (4) Callicorixa, White. 



4. Palar stridulator composed of pegs ranging in form 



from short peg-top shape to bristly, the transition 

 gradual . . . . • (3) GLiENocoRisA, Thomson.} 

 4rt. Palar stridulator composed of more regular pegs, 



never bristle-like, although elongate ... 5. 



5. Asymmetry to right. Pronotum and tegmina more 



or less rastrate . . . . (5) Arctogorisa, Wallengren. 

 5a. Asymmetry to left. Pronotum and tegmina smooth, 



shining ...... (6) Corixa, Geoffroy. 



Feinctles. • 



1. Face flattened 2. 



1(7. Face convex ........ 8. 



2. Shining, smooth ; pronotum without markings (2) Cymatia, Flor. 

 2rt. Piastrate, dull ; pronotum with impressed transverse 



lines . . . . . . (3) Gl.enocorisa, Thomson. 



3. Scutellum not covered, except at anterior margin, by 



pronotum . . . . . (1) Micronecta, Kirkaldy. 

 3fl. Scutellum concealed, except posterior angle, by pro- 

 notum ........ 4. 



4. Pronotum and tegmina smooth, shining . (6) Corixa, Geoffroy. 

 4rt. Pronotum and tegmina more or less rastrate . . 5. 



5. A conspicuous black spot on posterior tarsus (4 ) Callicorixa, White. 

 5 a. Posterior tarsi pale, fringing hairs often black (5) Arctogorisa, Wall. 



* " Notice sur un Insecte parasite " in Bull. See. Imp. Nat. Moscou, 

 vii. 392 (1834). 



f The chief generic character in this is that ui the female the face is 

 flattened. 



