302 NATURAL HISTORY. [CH. XXIII. 



most boundless extent of the subject, as affording 

 the materials of observation and of thought. 



The great Linne records in his immortal work, the 

 Systema Naturee, about 3,000 species, as the entire 

 number of insects with which he was acquainted ; 

 yet he afterward showed that Sweden alone pro- 

 duces about 1,700, thus leaving but a small number 

 as inhabiting the other portions of the world. The 

 great Ray, who wrote towards the end of the seven- 

 teenth century, believed that there might be 10,000 

 species of insects in the world ; but he afterward 

 increased this supposed number to 20,000. Now 

 the elaborate catalogue of British insects by Mr. 

 Stephens contains 10,000 named species, and in the 

 brief space which has elapsed since its publication, 

 about 2,000 have been added, making 12,000 at pres- 

 ent known to inhabit this country alone. The rapid 

 strides which this interesting science has made of 

 late years, have given rise to various speculations 

 as to the probable number of species existing in the 

 world, Mr. MacLeay conjectures that there are 

 about 100,000, while M. Decandolle estimates them 

 in the proportion of six to each phanerogamous 

 plant and fungus ; and as the number of these plants 

 is estimated at about 100,000, the number of insects 

 would be carried to the enormous sum of 600,000. 

 This estimate far exceeds the conjecture of Ray, 

 then considered a magnificent, although in truth a 

 very poor, idea of the host of creeping animals. 

 Messrs. Kirby and Spence seem to consider Decan- 

 dolle's supposition as somewhat exaggerated, and 

 estimate the number at about 400,000. The number 

 of species actually existing in cabinets would cer- 

 tainly exceed 100,000. 



To prove the rapid increase of the science, it may 

 be worth while to state the difference which exists 

 between the number of species in a few genera 

 known to Linnaeus, and that known to modern en- 

 tomologists. Thus, of the two genera, cicindeia and 



