COLORATION IN POLISTES. 4 1 



termined and will be considered in detail in the section devoted to the 

 geographical distribution of the species. They are in general along 

 the same lines as those just described for the texamis-rzibiginosus type. 



One collection comprising 21 specimens from a single nest (species 

 undetermined) shows variation in general coloration from a light red- 

 dish brown to a rich ferruginous. One specimen, a male, is conspicu- 

 ous for the rich red coloration of the mesothorax and the second 

 abdominal segment. The yellow borders are usually prominent, be- 

 coming obsolete from behind forward. In one specimen they were 

 entirely absent. The reddish-black zone of the abdomen is variable, 

 sometimes absent in all segments, sometimes present so as to obscure 

 wholly all the visible portions of the segments posterior to the second ; 

 there is a shallow triangle in the second segment, which varies from a 

 mere line somewhat dilated in the middle aspect to an area covering 

 one-third of the segment. Median yellow stripes are usually present 

 in the metathorax (in three specimens obsolete), but these stripes are 

 on a background which is obscured to a variable degree with black. 



Six specimens from a single nest, undetermined but intermediate in 

 size between the foregoing and riibigi7ios2is, show in general the same 

 variations. In all but two specimens the yellow is entirely absent in 

 the thorax, but is present in the metathorax in the faint border of the 

 postscutellum. 



C0NC1.US10N. 



From our study of individual variation in the genus, we con- 

 clude that all the species of Polistes are remarkably variable in their 

 color markings ; but the various species exhibit differences in their 

 degree of variability. These variations are continuous, proceeding by 

 insensible stages along certain definite paths. The conspicuously vary- 

 ing region of the body differs somewhat in the different types, depend- 

 ing primarily on the degree of melanism of the form ; but in spite of 

 this there is in all species observed marked positive correlation between 

 the variations of the conspicuously varying region and all other variable 

 regions of the body. 



