hungerford: aquatic hemiptera. - 111 



Gerris argenticollis Parsh. 1916. 

 ParsWey, Ent. Xews, vol. XXTII, 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 w^hite 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 broAvn. 



"Relative proportions: of antennal segments — 1st, 26; 2d, 13; 3d, 12; 

 4th, 10; of intermediate legs — femur, 50; tibia, 43; 1st tarsal segment, 

 20; 2d, 10. 



"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 

 biienoi) , median ventral (second) emargination narrow, senlicircular ; 

 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 Zoology, 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 w-as 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. Xews, 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., marginattis 

 Say, and G. buenoi Kirk., ventral view, q. v., in Ento. News, vol. XXYII, p. 103. 



