290 ZOO-GEOGRAPHICAL DISTRIBUTION [CH. 



still remains to be done on this fauna, and the number of species 

 is sure to be largely increased in the near future. The chief 

 features of the fauna are the numerous genera of Gomphini (if 

 indeed most of these can be accepted as anything more than 

 sub-genera!), the rich development of Tetrathemini, Trithemini 

 and Platycneminae, and the peculiarity of the Corduline and 

 Calopterygid faunas. It is very remarkable that there is an almost 

 total absence of entogenic Aeschninae, the only genus that can 

 possibly be considered entogenic being the widely-spread Hemianax, 

 possessing only one species. There is a close parallelism between 

 the Ethiopian and Oriental faunas in the following groups : 

 (i) Idocorduliini, (ii) Tetrathemini, (iii) Libellagini (Libellago parallels 

 Rhinocypha and Micromerus), (iv) Megapodagrioninae and (v) Platy- 

 cneminae. The fact that Protoneurinae are absent (except for 

 Disparoneura) coupled with the fact that the Ethiopian Platy- 

 cneminae possess some forms (e.g. Chlorocnemis) which are so 

 reduced that they might almost be classed as Protoneurinae, points 

 to the origin of the Old World Protoneurinae from a Platycnemine 

 stock. 



Madagascar. As in other groups of animals, so in Odonata, 

 this great island forms a very definite province, marked by many 

 special features. Out of 85 known species, 58 are peculiar to the 

 island, while all but six of the remainder are species occurring 

 only on the mainland of Africa besides. The fauna is distinguished 

 by the presence of seven genera peculiar to it, viz. Isomma, 

 Nesocordulia, Calophlebia, Neophlebia, Archaeophlebia, Neodythemis 

 and Nesolestes. 



The Oriental Region. 



This region includes the tropical parts of Asia south of the 

 Palaearctic region, Ceylon, Sumatra, Java, Borneo, Formosa, 

 the Philippines, and all the other smaller islands to the west of 

 Wallace's Line. Celebes, usually included in the Australian 

 region, may be regarded as Oriental as far as its low-lying coastal 

 regions are concerned, and forms a kind of "no-man's-land" 

 between the two regions. The geographical unconformity of the 

 region makes it difficult to give a satisfactory account of the 

 fauna. Apart from India, Burmah, and Cochin-China, every one 



