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 antennze conjoined without 
a trace of a suture between them. Tarsi two-segmented. The antennz 
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. Antennz 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. Antennz longer; third segment slender and very much 
longer than the second; fourth segment slender and sub- 
fusiform. 
D. Pronotum moderately constricted at the sides. 
M. brevis Champ. 
DD. Pronotum deeply constricted at the sides. 
M. leucostricta 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. brunnea 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 
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