A genus of Dragon-fly, _Onychogomphus_, has in Europe a somewhat similar distribution to _Claviger_, but it has besides a very extensive foreign range. There are altogether thirty-five species; of these ten are Holarctic, twelve Oriental, five Mascarene, and eight Ethiopian. The centre of distribution is therefore 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 Madagascar 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 _Orthoptera_--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 religiosa_). It occurs all over Southern Europe, and ranges as far north as the north of France. It is also found in Southern Germany 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 extremely ancient genus is testified by the fact of its presence in Mauritius, Japan, Australia, New Zealand, South America, and Madagascar. The genus _Bacillus_--to which the typical Stick-insects belong--has a somewhat similar geographical distribution. But no less than four species of _Bacillus_ are known from Europe, according to our great authority Mr. Brunner von Wattenwyl--all from the south; and some of these also range into North Africa. There are thirty-two other species distributed over Southern Asia, Africa, Australia, New Zealand, and the Sandwich Islands.
Volumes, indeed, might be filled with lists of species and genera of terrestrial invertebrates of Oriental origin, but I will not weary the reader with further enumeration of such instances. Just two more, however, before concluding, as I have not alluded to the large group of the _Arachnida_.