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 Gelastocoridse, Notonectidae 

 and Corixidae 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 like segment which is capable of being withdrawn into the 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 Corixidae. 

 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 Belostomatidae and Nepidae 

 are not used in these studies because these families are under 

 investigation by others. The genitalia of Corixidae 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 Notonectidae 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 



