THE ANATOMY OF THE ADULT MOSQUITO 



89 



the halteres or poisers, a pair of small, club-like organs, 

 consisting of a delicate stem terminating in a pear-shaped 

 head, which represents the rudiment of the hinder wings 

 of other insects. 



There appears to be good reason for regarding these 

 modified wings as sense organs, for although mere rudi- 

 ments, as far as their original functions are concerned, they 

 are supplied by one of the largest nerves in the body, and 

 have been regarded by Keller, Hicks, and Bolles Lee as 

 auditory organs. 





Fig. 21. — Semidiageammatic Drawing op a Teansveese Section op the 

 Thorax op C. pipiens (L). 



a, alar muscles ; b, portion of chitinous framework supporting the wing ; 

 c, coxal muscles ; d, dorsal vessel ; e, oesophagus ; /, flexor of abdomen ; 11, 

 nerve cords ; p, pneumatic vesicles. 



According to the last-named authority (" Les Balanciers 

 des Dipteres," Reciieil Zool. Suisse , I88b) , the organ consists 

 of a varying number of rows of minute vesicles placed at 

 the base of the organ, each vesicle being perforated and 

 containing a minute hair. Sense organs have been dis- 

 covered in a variety of very unexpected situations in insects, 

 and it is quite possible that, while the verticillary hairs of 



