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HEAD LENGTH (mm.) 
Fig. 2. Head width plotted against head length in the four forms of Cephal- 
onomia perpusilla females. 
the eyes very slightly smaller but the ocelli not noticeably reduced. 
The few available specimens (all from zone A, Table I) have the 
head, on the average, slightly wider than in the alate females, which 
is the opposite of what one would expect. As pointed out above, the 
mean head width/length ratio for the eight micropterous females is 
.75 (not plotted on Figure i) while that for the many alate females 
is .72. It is probable that a larger sample would reveal no difference 
in this respect. 
The subapterous females have the wings only slightly smaller than 
the micropterous females (about half to two thirds as long), a dif- 
ference barely noticeable in these minute insects. Yet the head shape 
is different and the eyes and ocelli generally smaller in the subapter- 
ous females. Whereas the mean head width/length ratio is .75 in the 
micropterous females, it is only .655 in the subapterous females. There 
FEMALES 
• MACROPTEROUS 
