110 THE UNIVERSITY SCIENCE BULLETIN. 
tinge of fuscous on the pronotum. Head of medium length, fuscous, cov- 
ered with silvery, scaly pubescence on the lower sides and beneath. The 
antenne short and stout, rusty brown, the second and third joints a little 
thicker and darker at tip, the second shorter than the apical, but longer 
than the third, the basal one a little longer than the superior line of 
head, the fourth a little shorter, dark in color and tapering towards the 
tip. "Rostrum swollen at base, reaching a little behind the anterior coxte, 
with the tip black. Pronotum with the anterior lobe quadrangular and 
flat, a very little shorter than wide, the anterior border a little thickened 
and raised, the middle line behind this depressed and marked with a 
short, yellow stripe, the posterior lobe evenly rounded off, a little flat- 
tened, destitute of a carinate line, lateral margins narrowly yellow; 
underside all silvery white. Legs of medium length, pale rusty beneath, 
the posterior femora as long as from the base of posterior coxe to the 
end of venter. Veins of corium prominent, two of the oval medio-apical 
areoles pale. Sutures of connexivum pale, outer half of the connexivum 
of the last three ventral segments including most of the segments them- 
selves and the cerci, yellow, the middle line of venter with four indented 
spots. 
“Length to end of anal segment, 10 mm. Width of pronotum, 2+mm. 
A single female was sent to me from Colorado.” 
Bueno in Ent. News, XXIV, page 21, has this to say about a female 
specimen from Garfield, Utah, taken on brackish water. 
“This agrees in every particular with the original description and 
with the type of the collection of the Colorado Agricultural Experiment 
Station of Fort Collins, kindly loaned to me for study by Prof. C. P. 
Gillette. This is the first authentic record of the species since it was 
first described, and serves to establish its character as a good species. 
Its chief superficial character separating it from Gerris (Limnotrechus) 
marginatus Say, lies in the anal cerci, which in marginatus are short and 
comparatively stout, while in gillettei they are long, attaining the ex- 
tremity of the abdomen and comparatively slender.” 
Distribution: Colorado, Utah, Montana, and California.w—Van Duzee. 
Gerris marginatus Say 1832. . 
Say, Heter. N. Harm., p. 36; Compl. writings, Le Conte ed., vol. L, p. 362. 
“Thoras with an elevated line: behind with an obvious depressed 
margin; abdominal margin dull rufous. 
“Tnhabits United States. 
“Body blackish, more or less tinged with olivaceous; thorax with a 
raised line, more elevated behind; lateral indented edge dull rufous; 
posterior depressed margin rather wide and very obvious; abdomen with 
the margin dull rufous; feet dull rufous; anterior thighs with a blackish 
line on both sides; coxe dull rufous beneath; beneath with a slightly 
elevated line, terminating anteriorly in a depressed one; blackish, with a 
silvery reflection. 
“Length over seven-twentieths of an inch. 
“Much smaller than the preceding (G. remigis) and more slender, of 
a darker color; abdominal margin of a different color, and the posterior— — 
margin of the thorax is broadly depressed. I obtained an individual, and 
Nuttall gave (me) one which he tcok in Missouri.” 
Localities: Quebec, Ontario, Maine, New Hampshire, Massachusetts, 
Connecticut, New York, New Jersey, District of Columbia, Virginia, 
North Carolina, Ohio, Michigan, Illinois, Missouri, Iowa, Kansas, wale 
rado, Manitoba, Colifornia and Oregon. 
