THE ORIENTAL MIGRATION. 269 



eight Ethiopian. The centre of distribution is there- 

 fore in the Oriental region, and we may assume that 

 in all probability the genus has originated there, 

 the European species having travelled west with 

 the Oriental migration at an early date of the 

 Tertiary Era. 



Ryothemis, another genus of Dragon - flies, has 

 originated perhaps somewhat farther east than the 

 last,, for no less than thirteen species are found 

 in Australia, a like number in India, five in Mada- 

 gascar and Africa, and five in the Holarctic region. 

 Both of these genera are entirely absent from 

 America, and they have possibly travelled to Europe 

 together. 



Among the European OrtJwptera the group to 

 which our Earwigs and Grasshoppers belong there 

 are also a good many instances of Oriental migrants. 

 One of the most striking of these is the curious 

 "praying insect" (Mantis religiosd]. It occurs all 

 over Southern Europe, and ranges as far north as the 

 north of France. It is also found in Southern Ger- 

 many and in Austria, and has a vast extra-European 

 range. There are even records of its occurrence from 

 all parts of Southern Asia and Java and a great part 

 of Africa. That it belongs to an extreme'y ancient 

 genus is testified by the fact of its presence in 

 Mauritius, Japan, Australia, New Zealand, South 

 America, and Madagascar. The genus Bacilhis to 

 which the typical Stick-insects belong has a some- 

 what similar geographical distribution. But no less 



