OF WASHINGTON. 115 



not many that are of any considerable bigness in the known 

 regions of the world have escaped the cognizance of the curious. 

 The number of birds he estimated at 500. The smallness of all 

 these estimates and the confidence which the author expressed in 

 their completeness are interesting at this day and in the light of 

 present knowledge. 



In the 1 2th edition of Linne's Systema Naturae (1767), on 

 the authority of Dr. Sharp something less than 3,000 species of 

 insects are listed, but no general estimate of the total number of 

 species seems to have been made by Linne. 



We have records of various estimates made early in the present 

 century. MacLeay estimated, about 1820, that the collections 

 of Europe contained some 100,000 species of insects, which was 

 accepted as correct by Latreille. Burmeister, however, estimates 

 the number at 80,000. Taking this last figure as a basis, Lacor- 

 daire (1838) estimates the proportion of the known species to 

 the unknown by orders and arrives at the conclusion that the 

 total number of species of insects is 362,000. This result he 

 also proves ( ?) by an estimate based on the number of plants of 

 the world. Taking De Candolle's estimate of plants for the en 

 tire globe at 110,000 or 120,000 species and supposing that there 

 would be on an average three insects to each plant, he finds the 

 total of insects to be between 330,000 and 360,000. A little 

 earlier Kirby and Spence, by a similar deduction, found the total 

 number of insects to be 400,000, which figure Lacordaire con 

 sidered to be too great. The only old estimate commonly 

 quoted is that given by Dr. John Day, in a letter to Mr. Spence 

 in 1853, in which the total number of insects is placed at 250,- 

 ooo species, a very considerable advance on the number fixed by 

 Ray, but much lower than the figures of an earlier period al 

 ready quoted. 



A number of estimates have since been made by various 

 writers, including Lord Walsingham, Dr. David Sharp, Profes 

 sor Riley, and others. In 1883 Dr. Sharp said: ''As a result 

 of a moderate estimate it appears probable that the number of spe 

 cies of true insects existing at present on our globe is somewhere 

 between 500,000 and one million." Dr. Sharp and Lord Walsing 

 ham, in 1889, extended the number of species of insects to a prob- 



