Séance du 1 Décembre 1921 119 



Tli(» mmibcr ol" joints being in this case also 

 i'ar larij^ci- in lîie adiilt tlinn in the \oung larva, 

 I sot to work lo iìiìd out wh(>ther this increase takes 

 place by successive divisions of the third joint as in 

 cockroaches or whether it follows other laws. 



Let us first study the antiMina of the male (fig. i). 

 Thnt of the adult bears two rows of lamellae which, 

 in the usual position, poinl, one forward and out- 

 ward and the other forward and inward. When pre- 

 pared in (lanada balsam, the antenna can either be 

 placed in profile in which case the two rows of 

 lamellae arc superposed (fig. 2), or be placed flat 

 when by pressing slighth the lamellae are spread 

 out (fig. 3). In fig. I, which shows the whole an- 

 lenna, only am) row of teeth has been drawn. The 

 following details should be noticed in figs, i and 2 : 



i" That there are tw^o basal joints, larger than 

 the others and entirely without teeth ; 



•>' That the teeth begin to appear as small pro- 

 jections starting from the /jth joint ; 



3° That tlie teeth lengthen rapidly so that at 

 the loth joint they have already reached their aver- 

 age size, that throughout tlie greater part of the 

 antenna they are very nearly identical then diminish 

 gradually from the fiSth or Goth joint till at the 7/ith 

 they have completely disappeared so that the last 

 five joints are entiriely without. 



It should further be noticed that with the excep- 

 tion of joints /j to 8 there is throughout a very obvious 

 regularity, the only difference being a gradual and 

 easily visible nan-owing au-tl ](Migtl»eriing of succes- 

 .<!ve joints. 



