4O COLORATION IN POLISTES. 



are somewhat narrowed, while both above and below the yellow lateral 

 spot may be entirely obscured by the darker color. Black occasionally 

 appears in the thorax in the position illustrated in Plate IV, fig. 38. 



P.perplcxus was first described by Cresson, who remarks that it may 

 prove to be only a male variety of nibiginosus. In general coloration 

 it easily passes into bellicosus. It has much more black in the meta- 

 thorax than bellicosus, but the amount varies ; yellow borders may be 

 greatly obscured or entirely lacking, and black appears in variable 

 amount in the anterior portion of the abdominal segments. 



P. generosus completes the transition to rubiginosus (PI. IV, fig. 39). 

 The yellow is usually entirely absent, but it may persist as a faint line 

 bordering the prothorax and metathorax. The mesothorax varies 

 through patterns similar to stages 22, 23, and 24, Plate II ; scutellum 

 and post scutellum are rusty red ; metathorax varies through a form 

 which is rusty red with a single median line through those with red 

 persisting in two or four zones to a uniform black, and black is again 

 variable in the anterior portion of the abdominal segments. 



NEST VARIATIONS. 



Six specimens of P. gc nerosus taken from a single nest show variation 

 in the depth of red- brown, in the prominence of the border of the first 

 abdominal segment, and in the thoracic markings. This species tends 

 to be uniformly very dark red-brown, but three zones in the mesothorax 

 approach black in their depth of coloring, while in one specimen whose 

 development was watched the degree of melanism is more marked still 

 and is represented in Plate 2, fig. 32. 



From the foregoing, and especially from the nest variations just con- 

 sidered, it is apparent that we have here a series which in the general 

 nature of the variability of the abdomen greatly resembles its northern 

 relatives, but we have added here another variable zone, viz, that of 

 the mesothorax, which in its type of variation is identical with the 

 Pennsylvania representatives of P. pallipcs, and relates itself, as we 

 shall see in the following chapter, by its ontogeny, to the color pattern 

 in all species. 



THE CAROLINUS TYPE. 



The species included here are smaller and less robust than those be- 

 longing to the texanus-rubiginosus type, and embrace the very smallest 

 representatives of the genus (PI. Ill, fig. 36). In coloration and type 

 of marking they greatly resemble the foregoing, except that the yellow 

 is never so prominent as in the tcxanus extreme of the series. 



The variations in the random collection from Florida have been de- 



