58 



COIrORATlON IN POLISTES. 



is transferred from fig. i8, and the corresponding curve constructed 

 from the data for the remaining segment is expressed alongside. Figs. 

 24 and 25 illustrate a similar relation in the specimens from Pennsyl- 

 vania and Florida. 



The coloration in the thorax varies along the general lines already 

 laid down for the red-brown and pallipes types. Certain regions appear 

 to be more stable than others. Thus the prothorax is prevailingly red- 

 brown for classes o, i, and 2, and prevailingly black in classes 4, 5, 6, 

 and 7, class 4 showing in several cases a limited red-brown area or a 

 slight red-brown stain on the posterior dorsal border. Class 3 is em- 



Fig. 20.— Expressing similar relation as in fig. 19 for material from Willow Grove, Pa. 

 classes the same as in figs. 18 and 19. 



phatically transitional in the females, being all black or all red-brown, 

 or having the two colors in varying proportions, while the males show 

 the usual yellow, with red-brown or black or both. 



The same tendency is expressed in the mesothorax. It is prevailingly 

 red-brown or red-brown with a slight median black line in classes o, i , 

 and 2, and, with one exception, is entirely black in classes 4, 5, and 6. 

 Pennsylvania, however, forms an exception to the condition for class 2. 

 Here the mesothorax is often variegated in the fashion already described 

 at length for the texayizis-riibiginosus type. In class 3 the mesothorax is 

 either all red, or all black or variegated in the manner just described. 

 The scutellum and post-scutellnm also show variation in pattern, but for 

 the purposes of this comparison we will confine attention to the variations 

 in the metathorax. 



