330 THE UNIVERSITY SCIENCE BULLETIN. 
onomy of this family and to prepare a monograph of it, a 
work in which he has been engaged for some time. 
A searching examination of some of the related families 
has shown some of them to possess quite specifically distinct 
genital characters. The males of Gelastocoride, Notonectidz 
and Corixidz have the genital claspers attached to a capsule- 
like segment which is capable of being withdrawn into the 
body and thus lies hidden. This strongly chitinized capsule 
is but loosely attached to the body wall and can therefore be 
drawn forth and removed from the bug in toto without the 
least injury or mutilation to the external features of the 
specimen. 
For these studies the specimen was first relaxed, then held 
under the binocular while the genital capsule was removed, 
an operation requiring considerable skill in some Corixide. 
The capsule was then placed in a vial of caustic potash and 
left until sufficiently clear for study. 
The drawings submitted herewith were made with a camera- 
lucida and all drawn to the same scale. The suranal plate 
and intromittent organ have been omitted in the drawings for 
sake of clearness. This paper is preliminary in nature and 
intended only to call attention to the possibility of using the 
genitalia of the males of some of the aquatic and semi-aquatic 
Hemiptera, a line of characters not hitherto used, in their 
taxonomy. The genitalia of the Belostomatide and Nepidz 
are not used in these studies because these families are under 
‘investigation by others. The genitalia of Corixide are not 
figured, for the reason that a completed study of the family 
by the writer will appear later. 
The genital segment bearing the male claspers in the Saldid 
is exposed and the removal of more than the claspers them- 
selves would mutilate the specimen. The Naurcorids ex- 
amined carry a relatively smaller capsule with claspers that, 
while different in shape in the two or three species studied, 
are not so strikingly distinct as in some of the other forms. 
Of the three families, having the genital capsule entirely 
hidden, the Notonectide have the simplest device. The capsule 
of a member of the genus Notonecta is erect and bilaterally 
symmetrical. The claspers, right and left, are about alike. 
The shape of the capsule itself as well as that of the claspers 
afford characters of specific value—as is shown by a study of 
