DISTRIBUTION OF ANIMALS 85 



of the Entomological Department of the Natural History 

 Museum. 



Insects of the World. 



Coleoptera (Beetles) .... 

 Lepidoptera (Moths and Butterflies) 

 Hymenoptera (Bees, Wasps, Ants, etc.) 

 Diptera (Flies, Gnats, Midges, etc.) 

 Rhynchota (Bugs, Cicadas, etc.) . 

 Orthoptera (Locusts, Crickets, etc.) 

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

 Several smaller Orders 



Number of Described 

 Species. 



120,000 



60,000 



45,000 



28,000 



18,000 



8,000 



5,000 



5,000 



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



If we consider that large areas of the most productive 

 tropical regions are still almost unexplored by the entomo- 

 logist, 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 

 estimate 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 Museum. His estimate then was 220,150 species of 

 insects. In the twenty-seven succeeding years, the Zoo- 

 logical 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 year by year, and 

 Mr. Shipley has therefore taken the number for the year 

 1897 as an average of the whole (8364 n.s.), and multiply- 

 ing this by 27 (allowing the odd 364 for synonyms) we 

 have an addition of 216,000, which added to 220,000 gives 

 ; a total now known of 436,000, an immense increase on the 

 estimate of Mr. Waterhouse. Of course a far more correct 

 way would be to add the number described as new, each 

 year of the twenty-seven ; but as this would involve the 

 counting of all the descriptions in thousands of pages of 



