138 ALICE M. BORING. 



(A}, and two almost as large (B. C), and most of them show a 

 small odd chromosome (X) slightly to one side in the group. 

 In Figs. 5 and 7, it is difficult to be certain which is the odd 

 chromosome. Two somatic cells from two of these same indi- 

 viduals show also the same similarity in chromosomes, two longest 

 and four almost as long (Figs. 20 and 21, A A, BB, CC). 



The same sort of study in Aphrophora spumaria gave the same 

 negative results. The somatic variation is great, but the chromo- 

 somes give no key to it. Fig. 26 is a plate from an individual 

 with light spotted wings, Fig. 27 from one with light tan wings 

 with no trace of spots, Fig. 28 one with dark spotted wings and 

 black abdomen, and Fig. 29 one with streaked wings with the 

 abdomen black on the sternites and yellow on the pleurites. 

 All have one largest chromosome (A). There are probably two 

 next largest as in Philcenus, but that is no distinction between 

 insects with different somatic characters. The only chance for 

 chromosome variation among individuals lies in the peculiar 

 small bodies shown in Figs. 34-37. These do not always stain 

 .as deeply as the chromosomes. They resemble somewhat the 

 supernumeraries described by Stevens 1 in Diabrotica, and Wilson 2 

 in Metapodius, but they do not here occur condensed in the 

 growth stages. There may be one, two, three, or four (Figs. 

 34-36). Whether this number is constant for each individual, 

 I could not tell, as the testes from several individuals with similar 

 wings and abdomen were preserved together. My material is 

 so limited for the study of this point that I place these few 

 drawings here in the hope that some one where the material 

 is available will take the trouble to collect it and work out this 

 point more thoroughly. 



SUMMARY. 



i. The chromosomes of Philcemis spumarius and Aphrophora 

 spumaria were studied and compared with those of the four 

 other species of Cercopidae previously worked out. All have an 

 odd chromosome which does not divide in the first spermato- 



1 Stevens, N. M., 1908, "The Chromosomes of Diabrotica vittata, Diabrotica 

 soror, and Diabrolica 12-pnnctata," Jour. Exp. Zoo/., V., p. 453. 



2 Wilson, E. B., 1909, "Studies on Chromosomes," V., Jour. Exp. Zool., VI., 

 ,p. 147- 



