260 Annals of the South African Museum. 



2. SYSTEMATIC AND DESCRIPTIVE PART. 



I. SUBORDER ZYGOPTEEA. 



Front and hind wings similar in outline and also in venation 

 (except for some minute details). In the basal part of wings between 

 M4< and Cu the quadrilateral (q), the proximal side of which is the 

 anal half of the arculus ; the quadrilateral free or crossed. 



Head transversely cylindrical, the hemispherical eyes separated by 

 a broad space, broader than the length of the diameter of each eye. 

 Median lobe of labium broader than lateral lobes, more or less bifid. 

 In the male sex two pairs of terminal abdominal appendages, the 

 lower pair being the sternite of the eleventh abdominal segment. 

 Female ovipositor consisting of two pairs of saws and a pair of 

 valves (p. 259). 



II. SUBORDER ANISOPTEEA. 



Front and hind wings dissimilar in outline and venation : the anal 

 field is more developed in the hind wing. The difference in the 

 triangular region of the front and hind wings is slight in the first 

 family of the Suborder, considerable in the second. Between M 4 

 and Cu in the region of the zygopterous quadrilateral there are two 

 spaces superposed in the transverse axis of the wing the supra- 

 triangular space (ht) and the triangle (t) ; the proximal side of ht is 

 the anal half of the arculus. Head roughly hemispherical or spherical 

 in outline. In the male sex a pair of superior terminal abdominal 

 appendages, and a single (often bifid) inferior appendage, being the 

 tergite of the eleventh abdominal segment. 



I. SUBORDER ZYGOPTERA. 



There is a marked difference in general appearance between a 

 zygopterous and an anisopterous dragonfly. With very little experi- 

 ence the observer will distinguish at a glance to which of the two 

 large and systematically equivalent groups a given insect may belong. 

 Zygoptera are comparatively weak insects ; their long and extremely 

 slender body, long and mostly very narrow, even petiolate, wings are 

 not suited to the wonderful display of flying power shown by many of 

 the Anisoptera. Their existence is more bound to the immediate sur- 

 roundings of their native waters, Avhere they cling to the vegetation, 

 take rather short flights, will rarely go very high up into the air 



