The Odonata or Dragonfties of Soiith Africa. 259 



The other type shows an elaborate boring mechanism, a terebra very 

 much like the same organ in many other groups of insects (Hymeu- 

 optera, Tenthredinoidea, Orthoptera and others). There are two 

 pairs of slender, acute saws, the lateral and somewhat anterior ones 

 belonging to the eighth sternite, the medial, posterior and smaller 

 ones to the ninth sternite. All four are, when out of function, 

 included between a pair of valves, derived from the ninth sternite, 

 and bearing each a slender, small, one-jointed process near its end. 

 This terebra is common to the entire Suborder Zygoptera and to the 

 Aeschninae in the Auisoptera. Its presence means that the insect will 

 deposit its eggs singly into holes made in dead or living plant tissues, 

 in the water or only near it, as the case may be. The eggs of the 

 valvulate groups, on the other hand, are laid entirely unprotected, 

 or only included in a mass of gelatinous matter or jelly, like frogs' 

 eggs. 



The relative position of the copulatory organs in both sexes involves 

 a complicated act of copulation. This act has attracted the attention 

 of naturalists from a very early time, and has often been described. 

 Nevertheless the knowledge of its more intimate details is of recent 

 date only. The most elaborate description, based on the statements of 

 other observers and a great many personal observations, is given by 

 Dr. Wesenberg-Luud in his paper already mentioned. The act may be 

 briefly described as follows: The male seizes his mate first with his spiny 

 feet, takes for a moment a position on the head of the female, at which 

 moment the spermatic fluid is transmitted from the opening on the 

 eighth to the copulatory apparatus on the second segment ; then the 

 male takes hold of its mate by the terminal appendages, which are 

 applied to the prothorax in Zygoptera, to the head in (at least most 

 of) the Anisoptera ; the female, somehow aided by the male, curves 

 her abdomen so that her genital opening will join the male's second 

 sternite, and the act is thus consummated. In most cases its later 

 stages take place on some supporting plant or even on the ground ; 

 but there are some curious and most remarkable cases (Libellula 

 quadrimarulata and depressa of the European fauna), where the entire 

 complicated function is performed when the two actors continue their 

 rapid flight, and in these cases it lasts only a few seconds. In other 

 cases it may last even for hours. 



Oviposition is also a very attractive study for the thoughtful 

 observer, and various different manners are described, the chief 

 difference being given, as already indicated, by the different structure 

 of the female organs ; but other differences scarcely less interesting 

 result from the local and seasonal conditions of each species. 



