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of the same insect. 1 From his experiments upon decapitated cock- 

 roaches, Graber concluded that these cerci were organs of smell. 



FIG. 183. Lyda larva: rt, head; //, end 

 of body seen from above ; c, from side, with 

 cercopod. 



Haase regarded these appendages, from 

 their late development and frequent reduc- 

 tion, as old inherited appendages which are 

 approaching atrophy through disuse. 



Cholodkowsky states that Tridactylus, a 

 form allied to Gryllotalpa, bears on the tenth 

 abdominal segment two pairs of cerci (ven- 

 tral and dorsal), and that the ventral pair 

 may correspond to the atrophied appendages 

 of the tenth embryonic segment of Phyllo- 

 dromia, with which afterward the eleventh 

 segment becomes fused. 



The cercopods are not necessarily confined 

 to the eleventh or to the tenth segment, 

 for when there are only nine segments, with the vestige of a tenth, as in 

 Xiphidium, they arise from the ninth uromere, and in the more modern cock- 

 roaches, as Panesthia, in which there are but seven entire segments, they are 

 appended to the last or eighth uromere. 



1 Amer. Nat., iv, December, 1870. 



