COLORATION IN POUSTES. 33 



The color characters of the wasp vary as a whole — there is marked 

 positive correlation between the dorsal and ventral surfaces of the 

 abdomen and between these surfaces and all other areas exhibiting a 

 tendency to vary. Finally, the species varies in a definite direction ; on 

 the one hand toward the xanthic aurifer of the West, on the other 

 toward the pallipes of the East. 



POLISTES VARIATUS AND RELATED SPECIES. 



The most marked afl&nities of P. variatus, as has just been indicated, 

 are for the species pallipes and aurifer. 



POLISTES VARIATUS AND POLISTES PALLIPES. 



In the case of pallipes the trend of variation is toward the type as 

 described by lycpeletier rather than any of the fourteen varieties given 

 by De Saussure (Description of Species, p. 79). This is significant. 

 P. pallipes (PI. Ill, fig. 34) has justly been considered one of the most 

 variable of the species of Polistes. Inspection of any large collection of 

 the species easily reveals the presence of most of the varieties described 

 and usually of some others which have not been described. Eighty 

 specimens collected from a single patch of golden rod at Willow Grove, 

 Pa., exhibit such great diversity of marking that it might almost be 

 said that no two are alike. The kind and extent of this variation will 

 be further considered in the section devoted to the geographical distri- 

 bution of the species in the United States. 



The resemblances between P. pallipes and P. variatus are closer when 

 we consider the representatives of P. pallipes as it occurs farther north. 

 We will therefore proceed to the study of nest variation in specimens 

 of P. pallipes from Eong Island. About 500 specimens of this species, 

 including ontogenetic stages, were secured at Cold Spring Harbor in 

 the summer of 1900. Our study here, however, will be confined to 

 200 specimens, 100 of which were collected at random and 100 directly 

 from the nest. 



Various types of color marking for the abdomen were selected and 

 the material grouped about them. It was found that the random col- 

 lection forms a series beginning with a form possessing on the sides of 

 the second abdominal segment large ferruginous areas which are con- 

 fluent with the broad ferruginous border. The yellow margins are 

 more or less obscure, but tend to persist in the first segment. This 

 type of marking represents the most xanthic condition for the collec- 

 tion. In the next stage the spots and borders gradually decrease, owing 

 to the encroachment of the black, the narrow yellow border still vary- 

 ingly present. From this we pass through a stage where the ferrugi- 

 3 



