HUNGERFORD: AQUATIC HEMIPTERA. 109 
“A great similarity exists between some of the species of this genus, 
and I have ventured to separate this species from the paludum F., which 
is said to have an elevated line on the thorax and another on the pectus 
and postpectus. 
“The thorax on the posterior segment is generally obtusely tinged with 
- dull yellowish, with a blackish longitudinal line in the middle. 
“Var. a. Thoracic elevated line rather more obvious; grey lines of 
the middle of the tergum more distinct. 
“Tnhabits Mexico.” 
Champion has given a much larger description in his Biol. Centr. Am. 
Heteroptera, II, p. 145. 
Distribution: Quebec, Ontario, Maine, New Hampshire, Massachusetts, 
Rhode Island, Connecticut, New York, New Jersey, Pennsylvania, Mary- 
land, North Carolina, Georgia, Louisiana, Michigan, Illinois, Colorado, 
Texas, New Mexico, Arizona, California and Oregon. 
Gerris orba Stal. 1859. 
Stal.-Freg. Eugen. Resa. Ins., p. 264, 1859. 
Distribution: California, Oregon and Nevada. 
Gerris conformis Uhl. 1878. 
Uhl., Proc. Boston Soe. Nat. Hist., vol. XIX, part IV, p. 435-436. 
“Dull olivaceo-fuscus, occasionally a little reddish-brown on the base 
of the pronotum; form rather more slender than that of H. remigis; the 
eyes more prominent. Pronotum invested with short, dense, olivaceous 
pubescence, the middle line of anterior lobe impressed orange; the pos- 
terior lobe coarsely, deeply, in places confluently punctured, with a slender 
elevated longitudinal line running along the whole length; lateral edge 
narrowly yellow. Antepectus pale yellow, powdered with white; under 
sides of the anterior and intermediate coxz and outside of the posterior 
coxe pale yellow. Medio and postpectus grayish sericeous. Hemelytra 
blackish brown, not reaching to the top of the ante-genital segment; 
tergum black, minutely, transversely wrinkled, the connexivum minutely 
punctured, lateral raised margin yellow, the apical processes slender, 
acuminate, as long as the segment to which they are attached. Venter 
cinnereous, sericeous minutely pubescent, the posterior margin of the last 
segment deeply concave, and together with the under side of the genital 
segments rufescent. Male: Length to tip of venter, 15-16 mm.; greatest 
breadth of pronotum, 2%4 mm. 
“The lateral margin of pronotum has a stout ridge terminating in a 
knob on the humerus, and between the humeri are two smaller protuber- 
ances, which are sometimes obsolete.” 
Distribution: Maine, Massachusetts, New York, New Jersey, Mary- 
land, North Carolina, New Hampshire and Connecticut. . 
Gerris robusta Uhl. 1871. 
Uhler, Am. Jl. Sci., ser. 3, I, p. 105, 1871. 
Distribution: Reported from California. 
Gerris gillettei, Leth. & Serv. 1896. 
Lethierry & Severin, Cot. Gen’] Hemip., vol. III, p. 60, (New name for L. productus Uhl.). 
Baker, Hemiptera of Colorado Agri. Exp. Sta. Bull. 31, p. 61. 
“Larger and somewhat more robust than L. marginatus Say, with 
long, somewhat flattened, anal processes of a yellow color forming the 
_ prolonged ends of the flat, broad connexivum, and is of the same color as 
the last three segments. Color of the upper surface dark brown with a 
