THE DISTRIBUTION OF AOTMALS 91 



To show the vast numbers and variety of the insect tribes, 

 I give here the approximate numbers of actually described 

 insects, kindly furnished me by Mr. C. O. Waterhouse of the 

 Entomological Department of the Natural History Museum. 



Insects of the World. Number of Described 



Species. 



Coleoptera (Beetles) 120,000 



Lepidoptera ( Moths and Butterflies ) 00,000 



Hymenoptera (Bees, Wasps, Ants, etc.) 45,000 



Diptera (Flies, Gnats, Midges, etc.) 28,000 



Rhynchota (Bugs, Cicadas, etc.) 18,000 



Orthoptera (Locusts, Crickets, etc.) 8,000 



Neuroptera ( Dragon-flies, May-flies, etc. ) 5,000 



Several smaller Orders 5,000 



Land Area, 48,000,000 square miles 240,000 



I 



If we consider that large areas of the most productive 

 tropical regions are still almost unexplored by the ento- 

 mologist, and that even in the best-known parts the less 

 attractive groups are very little known, it is almost certain 

 that the actual number of species of insects now in existence 

 is double that above given, while it may be three or four 

 times as many. 



To show how difficult it is to ascertain how many species 

 of insects are now known to exist, I give another recent esti- 

 mate by Mr. A. E. Shipley, F. R. S., in his Presidential 

 Address to the Zoological Section of the British Association 

 in 1909. This was based upon a careful estimate by Dr. 

 Giinther, in 1881, when Keeper of Zoology in the British 

 ^luseum. His estimate then was 220,150 species of insects. 

 In the twenty-seven succeeding years, the 7.ooJogical Record 

 gives the number of new species described in all parts of the 

 world. During the whole of this time the numbers described 

 have increased vear bv vear, and Air. Shiplev has therefore 

 taken the number for the vear 1897 as an averaa'c of the 

 wliole (8364 n.s.), and multijdying this by 27 ('allowing the 

 odd 364 for synonyms) we have an addition of 216,000, which 



