304 



Annals Eyitomological Society of America [Vol. X, 



than the rest. The drawing is from a fresh, completely 

 removed central nervous system. (Figure 2). 



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4; 



s 



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Fig. 1. Central nervous system of Campodea from above. X 10. 



Fig. 2. Central nervous system of Evalljapax from above. X 10. 



Fig. 3. Central nervous system of Machilis from above. X 10. 



Fig. 4. Central nervous system of Lepisma from above. X 10. 



Machilis has a more complicated brain, partly because of the 

 eye^connections ; it also has a general transverse direction, as 



