18 



THE CALIFORNIA SPECIES OF MEALY BUGS 



between these two lots of specimens belonging to the same species than 

 there is between any of the species previously discussed. It may, of 

 course, be asserted that we are here dealing with distinct species. It is 

 true that structurally these individuals are slightly different but the dif- 

 ferences are at the best small and are connected by a complete series of 

 intergrades. 



Fig. 10. Pseudococcus maritimus (Ehrh.) ; graphs of observed extremes (indicated 

 by heavy, broken line), including within them the graphs of individual an- 

 tennae of 13 other species (indicated by solid lines). 



In figure 10 the heavy, broken line indicates the observed extremes 

 of P. maritimus and included wholly or in large part within these ex- 

 tremes are the graphs of individual antennae of thirteen other species, in- 

 cluding such diverse forms as Trionymus calceolariae, Pseudococcus citri, 

 P. citrophilus, P. comstocki, P. crawii, P. krauhniae, P. longispinus, P. 

 pini, P. quercicolus, P. ryani, P. sallnus and P. virgatus. On the basis of 

 this graph any of these individuals might well be P. maritimus. 



It seems hardly necessary to pursue the matter further. I have ex- 

 pended so much space in attempting to show the futility of these graphs, 

 not because of any personal prejudice against the method, but from a 

 belief that its use can do nothing but perpetuate the confusion now exist- 

 ing in the systematic literature of this group. The material with which 

 the method deals is of such a nature as to preclude its use and there are 

 other and fully reliable characters upon which determinations of species 

 may be based. 



Legs. In many descriptions a considerable amount of attention has 

 been paid to the legs, their actual measurements in microns being given 



