HUNGERFORD: AQUATIC HEMIPTERA. 111 
Gerris argenticollis Parsh. 1916. 
Parshley, Ent. News, vol. XXVII, p. 103. 
“Dark, velvety brown above with fine sericeous pubescence. Anterior 
lobe of the pronotum with median and marginal yellow stripes, the 
former faint, the latter clothed with thick, silvery pubescence; posterior 
lobe with yellow margins. Inner margins of hemelytra marked at base 
with white between the veins. Under surface black or silvery, depending 
on the direction of the light; acetabula, bases of anterior legs and mar- 
gins of abdomen marked conspicuously with yellow; omphalium and 
legs, variable, black to pale brown. 
“Relative proportions: of antennal segments—lIst, 26; 2d, 13; 3d, 12; 
4th, 10; of intermediate legs—femur, 50; tibia, 43; 1st tarsal segment, 
BOs 2d, 1.0. 
“Thorax comparatively robust; abdominal spines not reaching apex 
of abdomen. 
“Male: Fifth abdominal sternite notched at middle of posterior mar- 
gin; sixth abdominal sternite not carinate, ventral surface of abdomen 
not distinctly. depressed just anterior to genital. segment (as it is in 
buenoi), median ventral (second) emargination narrow, semicircular; 
genital segment narrow. 
“Female: Lateral plates of genital segment together very slightly 
wider than long, widest at middle, carinate ventrally. 
“Length from tip of tylus to apex of abdominal spines, male 7.5 to 8 
mm.; female, 8 to 8.5 mm. 
“Holotype (male) and allotype (taken in copulation) in my collection; 
paratypes in the Museum of Comparative Zodlogy, Cambridge; Boston 
Society of Natural History; United States National Museum; and the 
Academy of Natural Sciences, Philadelphia. 
“Described from 10 males and 16 females taken at Forest Hills, Mass., 
April 26 and May 4, 1915, from a woodland pond, where it was associated 
with G. marginatus Say., and G. buenoi Kirk. A female specimen from 
Southern Pines, N. C., March 15, 1915 (Manee) belongs to this species. 
This form pertains to the subgenus Gerris. It is distinguished from 
G. buenoi and G. marginatus by the white markings at the base of the 
hemelytra, the form of the genitalia,* and the marginal stripes of the 
anterior lobe of the pronotum which are not silvery in the former and 
lacking in the latter.” 
Localities: Massachusetts and South Carolina. 
Gerris buenoi Kirk. 1911. 
Kirkaldy, Ent. News, vol. XXII, p. 246, 1911. 
Bueno, who submitted this paper after the death of Kirkaldy adds: 
“This species is a very near neighbor of Gerris marginatus Say., with 
which it has often been confounded in collections. Aside from the corre- 
lated structural characters, however, the flavescent margin of the an- 
terior lobe of the pronotum serves to distinguish it at once. It can also 
be separated by its smaller size, pronounced sutures between the ab- 
dominal segments, and more or less flattened abdomen in the male.” 
Localities: Quebec, Maine, New Hampshire, Vermont, Massachusetts, 
Rhode Island, Connecticut, New Jersey, Colorado and Manitoba. 
* Dr. Parshley gives drawings of the male genitalia of argenticollis Parsh., marginatus 
Say, and G. buenoi Kirk., ventral view, q. v., in Ento. News, vol. XXVII, p. 103. 
