XV] ZOO-GEOGRAPHICAL DISTRIBUTION 283 



of being archaic remnants. Ancestors of the group occurred at 

 Solenhofen in Upper Jurassic times. 



2. Subfamily Chlorogomphinae. This is another archaic 

 group, but not so typically palaeogenic as 1, since it is at present 

 confined to the Oriental region. Its distribution within that 

 region is, however, so discontinuous that it satisfies the definition. 

 The genus Chlorogomphus occurs in Sumatra and Java ; Orogomphus 

 is found in the Himalayas, in Borneo, and also in the Philippines ! 



3. Tribe Petaliini. In the forests of Southern Chili this 

 tribe is represented by six species, comprised in the genera Petalia, 

 Phyllopetalia and Hypopetalia. On the Blue Mountains of New 

 South Wales, a single species, Austropetalia patricia, occurs. This 

 might be claimed as a case of distribution from an original common 

 Antarctic centre. But the group is so clearly archaic, and had 

 such near relatives at Solenhofen in Upper Jurassic times, that 

 it is much safer to treat it as strictly palaeogenic. 



4. Subfamily Epiophlebiinae. We have here almost certainly 

 the very last stage in the distribution of a very archaic group. 

 The single genus Epiophlebia is represented only by a single 

 species from Japan! The genus seems to be a remnant of an 

 early Lestid fauna dating back to Jurassic times, and bears 

 somewhat the same relationship to Lestes that the fossil Hetero- 

 phlebiinae bore to our present-day Synlestinae. 



5. Subfamily Synlestinae. This group is represented by 

 two species of Synlestes in Eastern Australia, and five species of 

 Chlorolestes in South Africa. It is obviously an archaic group, 

 but is still fairly flourishing, and only in the first stages of dis- 

 continuity. The commonest species, Synlestes weyersi, ranges 

 from Victoria to North Queensland, and is in process of sub-division 

 into a number of regional forms or sub-species. 



The Entogenic Fauna. 



The entogenic groups, being essentially those which make up 

 the fauna peculiar to each region, must be dealt with separately 

 under the six main headings. I have thought it best to do this 

 by means of a complete table, which will serve the double object 

 of exhibiting at a glance the entogenic faunas of the six main 

 regions (and, in addition, those genera which are entogenic in 



