HEMIPTERA HETEROPTERA. 165 
11. GERRIS ODONTOGASTER. 
Gerris lacustris, var. e, Lair. Gen. iii. 133—Hydrometra odontogaster, Zett. 
H.-Sch. Wanz. Ins. ix. 73, pl. 301, f. 931. Fieb, Eur. Hem. 109— 
Limnotrechus odontogaster, Stal. 
North and Middle Europe. 
12. GERRIS ARGENTATA. 
Gerris argentata, Schum. Beitr. ii. 49. H.-Sch. Nom. Ent. i, 683—Hydro- 
metra argentata, H.-Sch. Wanz. Ins. ix. 74, pl. 301, f. 932. Flor. 
Rhyn. Liv. i. 740. Fieb. Eur. Hem. 109. Dougl. and Scott, Hem. 
568—Limnotrechus argentatus, S¢al. 
Middle Europe. 
13. Gerris SERVILLEI. 
Hydrometra Servillei, Meyer, Grei-Gessner. Milth. Schweiz. Ent. Ges. 
1864, 228—Limnotrechus Servillei, Stal. 
Switzerland. 
14. GERRIS ABBREVIATA. 
Hydrometra abbreviata, Pabr. Syst. Rhyn. 258. Stal, Hem. Fabr. i. 130. 
Pyrenees. 
North America. 
15. GERRIS APTERA. 
aptera, Schum. 
a—d, Illinois. Presented by F. Walker, Esq. 
e—h, Indiana. Presented by F. Walker, Esq. 
16. GERRIS FRANCISCANA. 
franciscana, Stal, Eug. Resa, Hem. 265. 
California. 
17. GERRIS ORBA. 
orba, Stal, Hug. Resa, Hem. 264. 
California. 
18. GERRIS ROBUSTA. 
Hygrotrechus robustus, Pack. Amer. Journ. Sci. 1871. 
California. 
West Indies. 
19. GeRRIS MARGINATA. 
marginatus, Guér. Icon. B. An. Ins. 351, pl. 57, f..2; Sagra, Hist. Cuba, 
Ins. 415, 
Cuba. 
