370 



THE CANADIAN ENTOMOLOGIST 



where the factor of time is considered, the earher year should 

 always appear at the left, and all vertical scales should read up- 

 ward. 



Figures 34 and 35 show map representations, which are common 

 and convenient ways of charting certain kinds of information. 

 Figure 34 illustrates the distribution by counties of two broods of 



BROOD 11,13^8 



Brood vi,i93X 



Fig. 35. 



Fig. 34. 



the Periodical Cicada in New Jersey. Distribution information 

 should always be placed before a reader in a graphic way, as only 

 in such a way can he grasp and visualize the material as a whole. 

 Where necessary, the detailed printed information can accompany 

 the chart, but it should never be used alone if one expects to con- 

 vince the reader. Figure 35 shows the distribution of the nursery 

 stock which entered New Jersey from other states during the fall 

 of 1916. In order to bring the localities out more clearly, the 

 dotted areas have been surrounded by heavy black lines. Both 

 figures 34 and 35 *are incomplete as to titles, which have been 

 omitted purposely to show the ineffectiveness of such a procedure. 



