36 COLORATION IN POLISTES. 



In 12 specimens this spot is touched with ferruginous, usually on 

 its anterior angle or antero-lateral border. The size of the spot and 

 degree of confluence varies, the extremes being represented b}' one 

 specimen where the spot reaches the anterior portion of the segment, 

 leaving only a narrow black line between itself and the preceding seg- 

 ment, all but meets its fellow in the middle line, and is confluent with 

 the segmental border almost the whole of its posterior extent ; and 

 another specimen where a black zone 2 mm. in width intervenes be- 

 tween the lateral spot and the anterior border of the segment. This 

 zone attains a width of i mm. between the spots, and further back 

 separates them from the segmental border for a distance of 2 mm. 

 The ventral side is marked similarly to the dorsal, but in most cases 

 it is not so xanthic, thus illustrating the general relation already de- 

 scribed as existing between the dorsal and ventral sides of P. variatus. 



The width of the middle stripes of the metathorax also varies. The 

 lateral stripes are entirely absent in this nest, though this is not the 

 case with all the members of this species. The clypeus here is uni- 

 formly yellow, only occasionally tinged with light ferruginous. 



An examination of a large series of P. aurifer from the West clearly 

 shows the relation of this pattern to that already described for P. va- 

 riatus. Taking the nest variation just considered as a basis, we see 

 that this species tends to vary in the direction of P. vatiahis. The 

 varying size of the yellow areas, the tingeing of these areas with fer- 

 ruginous, in a word, the same general type of correlation, is the most 

 striking feature of this relation. The nest collection is coherent and 

 exhibits greater unity than could easily be found to exist among any 

 20 specimens in a random collection. 



COMPARISON BETWEEN NEST COLLECTION AND COLLECTION AT RANDOM. 



The depth of melanism for nest collection is about midway between 

 that observed for southern California and Oregon. In the former case 

 the body color is predominantly yellow, the darker areas being greatly 

 restricted and represented in brown or red-brow-n. In the latter case 

 the yellow areas are greatly restricted, the darker areas spreading and 

 becoming more nearly black in hue. Specimens from this part of the 

 United States are identical with the type of P. variatus. 



All the specimens from Idaho, Utah, Montana, and Nevada which 

 I have seen are in general similar to those from corresponding lati- 

 tudes along the Pacific coast ; but this section of the country is but 

 meagerly represented in the general collections, and I have no doubt 

 that more careful study would reveal a great degree of local variation 

 for this species. 



