4 INTRODUCTION. 



" The abdomen of the EJiyncJiota, in its greatest development, con- 

 sists of nine segments placed one after another, of which only the 

 first 6 are proper abdominal segments, the last 3 (of which the 1st 

 and 2nd are often entirely wanting) differ in form, more or less, from 

 the others and subserve the functions of the sexual organs. In every 

 ease, therefore, for the sake of analogy, I call only the first six, Ab- 

 dominal-segments, and the following ones, Genital-segments. In the 

 male in some families (Anthocoridce, Capsina,) we find, apparently, 

 seven abdominal segments, as the first genital segment retains 

 entirely the form of an abdominal segment. In the female of the 

 Lygceoda, some of the Coreoda (Coreus, Pseudophlceus, Syromastes), and 

 Aradus, the 6th abdominal segment on the underside participates in 

 the sexual functions, in like manner as the following genital seg- 

 ments ; thus in the middle it is sometimes entire, sometimes cleft 

 almost up to the anterior margin, in such a manner that the edges of 

 the cleft touch or overlap each other. Often in the female, mostly in 

 those instances where the ovipositor is largely developed, the last 3 

 abdominal segments (in the Lyg&odce the fourth and fifth) are broadly 

 raised up and in the middle concealed under the foregoing segments, 

 so that they can only be distinguished at the sides. In the male on 

 the contrary the last 3 abdominal segments, in the middle, on the 

 underside, are not hidden under the foregoing segments, but are 

 visible. In counting the abdominal segments, we must observe, that 

 viewed from beneath (in $ and ) it is generally, nearly, or quite im- 

 possible to see the first of them, since it is shorter than the other 

 segments, and partly concealed, the front being covered by the 

 posterior margin of the metasternum and the hinder coxae, and the 

 hinder side anchylosed with the second segment. Nevertheless, in 

 such cases, when the wings are removed, the separateness of the 

 segment is always clearly perceptible on the upper side, so that we 

 can count six abdominal segments on the upper side and only five 

 beneath. Consequently in the male there are all the six abdominal 

 segments, and in the female always the first five at least, and mostly 

 also the sixth, exclusive of the genital segments. 



"Following the abdominal are the genital segments, in their 



