Si-ance du 20 Avril im 



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vana li;i\e lS-19 joints ii! Ujc nuilc and lo-14 in [\\v 

 female (figs. 4 and 5). The fact which concerns as 

 from tlie point of view of growth is tlie appearance of 



Fii;. 4. Perijilaneta americana : Adult male. Ventral view, 

 to ßhow the styles and the cerei x 4. 



Fig. 5. Periplaneta awericana ; Adult female. 

 view, to show the cerei x ^■^■ 



Ventral 



the cerei in the newly hatched insect. The specimens 

 i examined were two yonng P. americana which had 

 just hatched, 5.5 millimetres long and 11 \oiing from 

 5.5 to 6 mm., all males. In every case the cerei were 



