2O4 EDMUND B. WILSON. 



female groups clearly show 24 chromosomes, of which two are 

 of the same relative size as the unpaired one of the male. Two 

 of the ovarian groups, typical of many others observed, are shown 

 in Fig. i, e, f. These facts show that Pyrrochoris conforms to 

 the ordinary type in which the male has an odd chromosome, as 

 in Anasa, Protenor, Alydus, Largus and. many others. 



COLUMBIA UNIVERSITY, 

 January 23, 1909. 



