Revision of the Notonectide. 401 
25 (23-24) Notocephali margines laterales curvate et sinuate ; 
abdominis dorsum haud coccineum. 
26 (31) Species magne, robuste. 
27 (28) Posterius ampliata ; membranz lobi inequales. 
(Europa) 18 lutea, Miill. 
28 (27) Posterius haud ampliate ; membranz lobi subzequales. 
29 (30) Caput, pronotum, scutellum nitida nigra (hemielytra 
rubronigra) . ‘ : . (Brasilia) 17 nigra, Fieb. 
30 (29) Caput, pronotum, scutellum non omnino nigra. 
(Regiones palearctica tota, orientalis in parte) 
16 glauca, Li. 
31 (26) Species parvee, subrobustee. 
32 (33) Pronoti basis subrecta. 
(America bor. et merid.) 8 undulata, Say. 
33 (32) Pronoti basis aperte concavocurvata. 
(Australia) 6 hundlirschi, Kirk. 
1. Notonecta mexicana, Am. Serv. 
Notonecta mexicana, Am. et Serv., 1843, Hist. nat. 
Ins. Hém., p. 453, pl.viii., fig. 7; Herr.-Schiiff., 1853, 
Wanz.'Ins., ix., p. 43, ple 294, fic. 903; Uhl., 
1886, Checklist Hem.-Het. North Amer., p. 28. 
N. klugu, Fieb., 1851, Abh. bohm. Ges. Wiss. (5), 
vil., p. 474. 
Head narrow at base, parallel for a short space, then sinuately 
diverging ; vertex from three to four and a-half times as wide as 
synthlipsis. Pronotum very transverse, about two and a-half 
times wider than long, lateral margins slightly sinuate, humeral 
margins gently and elongately curved, posterior margin not sinuate ; 
humeral angles acute, accentuated. JM/etanotum not quite half as 
long again as scutellum, black (dark vars.) or violet-brown, mar- 
gined with luteous (pale vars.). Hemielytra varying in colour, 
membrane-lobes subequal. Ale semitransparent, smoky, nervures 
brown (pale vars.), or semitransparent smoky black, nervures 
blackish-brown (dark vars.). Abdominis dorsum black (dark vars.), 
or rufoluteous with paler genital segments (pale vars.). Abdominis 
venter varying from black to testaceous. 
Long. 11-14 mm., lat. 4°5-4°8 mm. 
Hab. America: Western United States; Mexico ; 
Costa Rica; Colombia. 
The types of N. mexicana and N. klugii appear to be 
lost. 
