COLORATION IN POLISTES. 13 



The prevailing or modal condition of each class of abdominal mark- 

 ings is represented in the center of each diagram, the area of the 

 circle a bearing the same relation to the other areas as the number of 



7 



FIG. 7. Diagrammatic representation of relations of types of color pattern for the abdomen of 

 Polistes variatus. The areas of the various circles and portions of circles bear the same 

 relation to one another as do the number of specimens found under each type. 



a. Modal condition for dorsal surface of second abdominal segment. 



a,b,c,d. A series of transitions to the maximal melanic condition. (PI I, figs. 3and4.) 

 Here ferruginous encroaches on the yellow, and, in turn, becomes obscured by black. 



a, b', c', d. A second series of transitions to the maximal melanic condition. Here the 

 black encroaches directly on the yellow. (PI. I, figs. 5 and 6.) 



a, b", c". A. series of transitions to the maximal xanthic condition. (PI. I, fig. i.) 



a, b"', c"', d'". A series of transitions to a melanic condition, where the prevailing tone 

 is fuscous. (PI. I, figs. 7 and 8.) 



b"", c"". A number of forms transitional between *, c, d, and b'", c'" , but, owing to a 

 larger area of ferruginous, forming a class somewhat by themselves. 



specimen's in this class bears to the number of specimens in each of the 

 remaining classes. This type of abdominal marking may be described 

 as a very dark fuscous (practically black) with well-defined medially 



