hungerford: aquatic hemiptera. 83 



Genus MERRAGATA White 1877. 



Description of Genus. Much like Hebrus but differs from it in hav- 

 ing the fourth and fifth segments of the antennae conjoined without 

 a trace of a suture between them. Tarsi two-segmented.. The antennae 

 are four-segmented, the minute segment at the base of the third segment 

 of the antenna not being counted as a true segment, but as part of the 

 third. Heads of the Mexican and Central American species have either 

 a fine or a distinct median longitudinal groove, while the Nearctic 

 forms have the head with two longitudinal grooves, converging anteriorly, 

 and a median ridge between these grooves. Dimorphism seems to be 

 characteristic of the genus, macropterous and brachypterous forms oc- 

 curring in the same species, the latter form having only short wing 

 pads that vary somewhat in size in the same species and in the different 

 species. 



KEY TO SPECIES OF MERRAGATA. 

 (From Drake.) 



A. Apex of scutellum bifid, antennal segments two to four subequal, 

 the basal segment shortest and stoutest. , 



M. lacunifera Berg. 

 AA. Apex of scutellum not bifid. 



B. Head with either a faint or a distinct median longitudinal 

 groove. 



C. Antennae short, less than twice the length of the head; 

 segments from one to three subequal, the fourth rather 

 stout and fusiform. M. hebroides White. 



CC. Antennae longer; third segment slender and very much 

 longer than the second; fourth segment slender and sub- 

 fusiform. 



D. Pronoturn moderately constricted at the sides. 



M. brevis Champ. 



DD. Pronotum deeply constricted at the sides. 



M. leucostHcta Champ. 



BB. Head with two longitudinal grooves converging anteriorly 

 and with a median ridge between these grooves. 



C. Pronotum moderately constricted at the sides, the disc 

 with a broad, deep, longitudinal furrow; color blackish, 

 the hemelytra white with distinct dusky patches. 



M. foveata Drake. 



CC. Pronotum more abruptly constricted, the disc with a 

 shallower groove; color reddish-brown or dark reddish- 

 brown, the dusky patches of the hemelytra evanescent. 



M. br 1171716 a Drake. 



Of these six species only two are recorded for the United States. 

 These were described by Drake and are given herewith : 



Merragata foveata Drake 1917. 



Merragata foveata Drake, the Ohio Journ. Sci., vol. 17, pp. 103-104. 



"Very like M. hebroides Champion in size, color and antennal char- 

 acters, but readily separated from it and the other Mexican and Central 

 American species by having the head bisulcate longitudinally and with a 

 distinct median ridge between these furrows. From its only Nearctic 

 congener, M. brunnea Drake, it is easily recognizable by the less abruptly 



