CHROMOSOMES OF THE CERCOPID^E. 315 



The eight species of Cercopida in which the spermatogenesis 

 has so far been studied belong to four genera. The chromosome 

 number (reduced) varies from 7 to 15. The chromosome number 

 seems to have no significance for family or genus. The specific 

 numbers are shown in Table I. 



The odd chromosome in the spireme stages differs in its shape 

 in the genus Aphrophora from that in the other genera as far as 

 studied. It is a much elongated structure early in its appearance 

 in Aphrophora, while it first appears as an oval or round body in 

 the others. 



All eight species of the Cercopidae studied show a typical odd 

 chromosome, which divides only in the second spermatocyte 

 division. In all of the species except Aphrophora quadrinotata and 

 Clastoptera proteus, in which the material was limited and the 

 equatorial plates consequently not studied in favorable positions, 

 there is one chromosome among the reduced number which is 

 distinctly larger than the others. In no case is the odd chromo- 

 some the largest one. 



WOODS HOLE, 



July 30, 1915- 



