188 



Annals Entomological Society of America [Vol. XV, 



13 pores. In the posterior lateral groups of the apple form the 

 number of pores found to occur most commonly, then, is 12. 

 Therefore, speaking technically, 12 is the "mode" of the apple 

 form. The curve for the posterior lateral groups of the lilac 

 form is based on counts of the pores of 485 groups. Of these 

 groups, 64 (13.19% of the total number of groups examined) 

 had 19 pores. The mode of the lilac form, then, is 19. Not a 

 single group of the 485 examined from lilac had 12 pores, while 

 only six (1.20%) of the apple specimens had 19 pores. 



Fig. 1. 



10 U 14 16 IS fO 22 24 26 28 

 NUMBEH, or POW:^ IN A GHOUP 

 _ LILAC 



30 32 34 



Fig. 2. 



10 12 14 16 IS 20 [I 24 26 28 SO dl 34 

 Mmilt OF POSi-S TU A GIOUT 



Fig. 1. Curves showing variation in the number of circumgenital pores of the 

 posterior lateral groups of the apple and lilac forms. The curves are 

 based on counts of the pores of 496 groups of the apple form and 485 

 groups of the lilac form. 



Fig. 2. Curves showing variation in the number of circumgenital pores of the 

 anterior lateral groups. The curves are based on counts of the pores 

 of 490 groups of the apple form and 485 groups of the lilac form. 



