THE TUORAX OK TKt-NK. 



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HOOIvS ON 'IHE 150RDERS OF THE WINGS OF IXSECTS (SPHE- 

 CODES). 



The spaces between the Acins and veinlet8 are called 

 cells. 



The number and situation of these veins and their 

 branches are ot" great importance in determining genera 

 and species. 



Many insects liave their wings divided into three 

 parts by the arr.-nigement of these veins, i. <?., the costal, 

 or upper e<lgo of Ihe wing; the 'median^ the lo'\>er '<xn^ 

 central part of tlio wing— the largest of the three, and, 

 in the grasshuppcr and cricket, sometimes modified to 

 form a musical organ ; and the internal area, which is 

 placed between the otl;cr two, and is the smallest, and 

 least distinctly marked of the three. 



ifUSICAL INSTRUMENT OF THE GRASSHOPPER ( ACRID a). 



A, upper surface of right wing case ; B, under surface of left 

 wing case ; C, file, more highly magnified. 



