THE ANIMAL KINGDOM. 



101 



is subjected to their empire, and only avoids tlieir attacks 

 by adapting his abode and manner of living to the emer- 



51. Mosquito highly magnified — C'ulex'^ (Linn.); Simulium (Humboldt). 



gency. At the time when the mosquitoes are most 

 prevalent in Senegal, the negroes, notwithstanding the 



^ There are many species of gnats, distinguished by the generic name Culcx, 

 but all having a similar conformation and similar habits. The species found in 

 foreign countries are generally known as mosquitoes ; but mosquitoes and gnats 

 are the same thing. 



The weapon with which the gnat makes its attack is a long and slender pro- 

 boscis, which projects from the mouth like a very fine bristle, appearing to the 

 naked eye quite simple. Under the magnifying power of the microscope, how- 



N 



f'J '''Kl'ii 



52. Organs of the Mouth of On.'it. 



ever, it is seen to be a flexible sheath {i) inclosing six distinct pieces, two of 

 which are cutting blades or lancets (g), two notched like a saw with reverted 

 teeth (/), a tubular canal (e), and the central one an excessively acute point, 

 which is also tubular {d). When the attack is made, the gnat brings the tip of 



