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

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



FIG. 1S3. Lyda larva: a, head; b, 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 tsvo pairs of cerci (ven- 

 tral and dursal), 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 eercopods are not necessarily confined 

 to the eleventh or to the tenth segment, 

 for when there are only nine segments, with the vestige 

 Xipliidium, they arise from the ninth uromere, and in the 

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

 appended to the last or eighth uromere. 



of a tenth, as in 

 more modern cock- 

 segments, they are 



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



