CONTENTS. 



Page 



Introduction j 



General account o 



Individual variation in the color pattern of Polistes 1 1 



Polistes vai-iatus Cresson 12 



General type of variation 12 



Distribution of material among the various types 14 



Degree of variability in males and females 15 



Nature of the variation in a single nest 16 



Relation of color pattern to the time of emergence 20 



Correlations between pattern of abdomen and other color characters. 21 



Summary ,2 



Polistes variatus and related species 33 



Polistes variatus and Polistes pallipes 33 



Polistes variatus and Polistes aurifer 35 



General conclusions concerning relations of Polistes variatus 37 



Variations in other species of Polistes 38 



The texaniis-ruhiginosus type 30 



The carolifius type .... 40 



Ontogenesis of the color pattern 42 



Development of the pattern in Polistes variatus 42 



Development of the pattern in Polistes pallipes 43 



The red-brown species 44 



Physical and chemical nature of the pigment 45 



Chemical examination of the pigment 47 



Comparison with the color phenomena of butterflies 52 



Geographical distribution of types of color marking 53 



Distribution in the United States 53 



'^yp^^ 53 



Distribution of types rr 



Relation between latitude and amount of dark pigment in Polistes. . . 56 

 Correlation between pigmentation of second abdominal segment and 



the segments posterior thereto 57 



Correlation between markings of second abdominal segment and cly- 



peus of female 5o 



Distribution in Europe 63 



Distribution in South America 57 



Distribution in Africa 68 



Distribution in Australia and the East Indies 69 



General laws governing differentiation 70 



Individual variation under varying external conditions 72 



Types of coloration in related genera n-i 



Considerations with respect to various theories of evolution 75 



Summary and conclusion 77 



Description of species 7q 



Bibliography 3- 



