422 DISTRIBUTION IN SPACE AND TIME 



these " halolimnic " forms, some to all appearance closely resem- 

 bling ancient extinct types, are now found in the fresh waters of 

 this lake, side by side with ordinary freshwater species. 



Ethiopian Insects [Insccfa). — The region is very rich in insect 

 life, but it is not possible here to enter into details regarding 

 the many interesting and beautiful species. Wallace mentions 

 the large and handsome Goliath- Beetles as being especially 

 characteristic, and some of the complex societies of African 

 Termites have been spoken of elsewhere (see p. 124). 



Fauna of Madagascar. — This subdivision of the Ethiopian 

 region calls for a few remarks, since it is one of the best existing" 

 examples of an ancient continental island connected in remote 

 times with the adjacent continent. There can be no doubt that 

 a large part of the Mascarene fauna has been derived from the 

 mainland of Africa, but Madagascar became isolated at a time 

 when that continent did not include among its inhabitants many 

 of the animals by which it is now characterized. Long-standing 

 isolation has also resulted in the evolution of many peculiar 

 species, some of highly remarkable kind. Both the positive and 

 the negative characters of the Mascarene fauna are best illus- 

 trated by reference to the Mammals and Birds. 



Mascarene Mammals {Mammalia). — Of the sixty-six species 

 of Mammals native to Madagascar about half are Lemurs 

 {Lciniij-oidca), representing no less than nine peculiar genera 

 {Lemnr, C/iiroga/ens, Sec), of which one {Chiromys) includes the 

 remarkable Aye-Aye. Except for about fourteen small species 

 shared between the continent of Africa and the Oriental region, 

 these ill-defended creatures are found nowhere else, and their 

 abundance in Madagascar is no doubt to be attributed to the 

 scarcity of carnivores in that island. The case is on a par with 

 that of the Pouched Mammals of Australia. With the single 

 exception of a Shrew, all the Insect- Eaters {Insectivora) of 

 Madagascar belong to the peculiar family of Tanrecs [Centetidie), 

 while the few Gnawers [Rodentia) are rats and mice, all belong- 

 ing to distinctive genera. Flesh-Eaters {Carnivora) are only 

 represented by the Foussa {Crypt oprocta) and eight kinds of 

 Civet-Cat. Of Hoofed Mammals {Ungnlaia) there is only a 

 species of River- Hog {Potamoc/iccrns), although the Hippopo- 

 tamus is known to have been once indigenous. The charac- 

 teristic Apes and Monkeys, most of the Flesh-Eaters and Hoofed 



