TAXONOMIC VALUE OF MORPHOLOGICAL CHARACTERS 



15 



average of the other. Still it is fair to ask to what extent these graphs 

 would be of aid did we not already know the two species to be distinct. 



Fig. 4. Pseudococcus ryani (Cog.) and P. sequoiae (Coleman) ; antennal graphs 

 drawn from specimens taken from various hosts and localities; position of 

 graphs as in fig. 3. 



Text figure 4 presents the graph obtained by using all the available speci- 

 mens of these two species from different hosts and localities. It will be 

 noted that the gap between the two graphs has entirely disappeared, 

 although the average graphs would still lie quite far apart. Again it is 

 fair to ask if anyone would separate these species on the basis of such a 



Fig. 5. Pseudococcus longispinus (Targ.) ; antennal graph drawn from specimens 

 taken from various hosts and localities. 



