r/zf- Odoiiata or Brcujonflieii of South Africa. 383 



common where they occur, aud little given to hiding; although swift 

 flyers, they often settle on vegetation or on the ground, and are there- 

 fore an easier prey than Aeschidnae or Corclulinae ; many of them 

 are not very jsartieular aliout the kind of waters they inhabit, the great 

 majority preferring standing water, from large areas down to pools 

 and swamps. Most species are wide ranging, some occurring over 

 immense areas, either without any appreciable differences or with 

 division into subspecific forms in various degrees of divergence. Three 

 species of the present fauna occur as well in South Africa as in 

 Mediterranean Europe {Orthetrum chrysosikjma, Crocothemis eryfhrciea, 

 Sympetrum Fonscolomhei) ; others are more of the inter-tropical type 

 aud occur only at the frontiers of both faunae — European and South 

 African, but not commonly {Orthetrum irinncria, Trifhemis annulata) ; 

 a good nunilier are common to the entire African continent, or at least 



Pig. 6S. — Oriheirvm trinarriii, ^. East ATrica. Genitalia, second seg 

 ment, left side 



to the region south of the desert lielt ; others are found even beyond 

 this limit in parts of tropical and sub-tropical Asia, etc. 



The subfamily is morphologically a very homogeneous unit ; there 

 are many constant and important differences in venation between 

 genera and groups of genera, l)ut the differences are mostly slight or 

 inconspicuous, aud were almost overlooked by the earlier systematists, 

 who found great difficulties in subdividing the great and homogeneous 

 group. From various reasons — morphological, biological aud geo- 

 graphical — we may safely conclude that Lihelhilinae are a caenogenetic 

 group, flourishing and in full development in the present age of the 

 glol)e. In this respect they have in the suborder Zygoptera a f)arallel 

 in the subfamily Agrioninae, more especially in the " Legion Agrion." 



Libelluline nymphs are of remarkably uniform type. Body short, 

 dorsal surface moderately convex. Lalnum short ; lateral lobes broad 

 and convex, their mesial margins touching in a long line, the whole 

 forming when stretched out a spoou-like structure, with long and stiff 



