286 ZOO-GEOGRAPHICAL DISTRIBUTION [CH. 



more than one region), and of giving, in a fairly compact form, 

 a full list of genera for all the subfamilies and tribes, except, 

 of course, the five dealt with above in the Palaeogenic Fauna. 

 By combining this table with the classification given in chap, xiv, 

 the student can not only obtain at once a full list of genera for 

 each tribe, but at the same time he will be able to note the distri- 

 bution of those genera. The table is supplemented by a short 

 discussion on the chief characteristics of the autochthonous fauna 

 of each region. 



The Neotropical Region. 



This region includes the whole of South America and adjoining 

 islands, Centra^ America and the tropical parts of Mexico, and 

 the whole of the West Indies. It is, in the Odonata as well as 

 in other groups of animals, the most self-contained of all the six 

 regions of the earth. Out of 135 genera known to occur, no less 

 than 111, or 83 per cent., are peculiar to or entogenic in the region 1 . 

 Being for the most part a tropical region, it is exceedingly rich 

 in Odonata. The total number of species described from it far 

 exceeds that of any other region, as also does the total number of 

 entogenic genera. 



A glance at the table shews us how the various subfamilies 

 and tribes are represented in the region, so that it is not necessary 

 to go into details here on that point. We shall, however, notice 

 the more striking peculiarities of the region. With the exception 

 of two genera (Hagenius and Sieboldius) the whole of the Gom- 

 phoides-Seiies of the Ictinini is confined to Neotropica. A similar 

 distribution holds for the Palpopleurini, the Uracis-Series of the 

 Brachydiplacini, and the Dythemis-Seiies of the Trithemini. The 

 whole of the New World genera of the Megapodagrioninae, 

 Protoneurinae, Teinobasini and all but one of the New World 

 Pseudagrionini also belong to this region. The Thorinae and 

 Pseudostigmatinae (PL I, fig. 8) are exclusively confined to Neo- 

 tropica. As against this wonderful wealth of forms, we notice 

 a great paucity of Corduliinae and a complete absence of 

 Platycneminae. The Corduliinae are essentially a temperate group, 



1 In calculating these " Regional Percentages *' for the six regions, genera 

 which are entogenic in more than one region have been excluded. 



