1896,] NATURAL SCIENCES OF PHILADELPHIA. 43 



Now the females of this series (that of lepachidis being unknown) 

 separate at once into those with broad distinct yellow abdominal 

 bands, and those with the abdomen only spotted. The former are 

 from HeManthus (rarely from Verhesina), the latter very abundant 

 on Verhesina. But now we find, to our surprise, that some of the 

 males with yellow on the abdomen belong to the spotted females, 

 and come from Verhesina ; while others (with the dark flagellum) 

 belong to the well banded Helianthus females. Further than this, 

 other males without the yellow belong to other well banded Helian- 

 thus females from a different locality. Thus among the Helianthus 

 forms (alhipennis) the females from two localities (La Junta and 

 Las Cruces) are hardly at all different, while their males are 

 decidedly different ; and the male of the Las Cruces form more 

 resembles the $ of verhesince, which is common on Verhesina in 

 the same locality. But the Las Cruces males differ from verhesince 

 in the color of the flagellum ; while the La Junta males, differing 

 from verhesince in the abdomen, resemble it in the antennae ! The 

 difficulty is still further increased by the occurrence of individual 

 varieties presenting other combinations of the "specific" characters. 

 In such a case as this we should be hopelessly adrift without bio- 

 logical observations. There is no apparent reason why the varia- 

 tions in clypeal markings should not be just as " specific" as those 

 in the color of the flagellum, or (as in lepachidis) in the color of 

 the head and thorax. Mr. Fox, after examining a series, concludes 

 that we do not know the $ of alhipennis, and that my alhipennis 

 $ , verhesina' and lejmchidis are all varieties of hyalina. But all 

 this is contradicted by actual observation of the insects on the flow- 

 ers. The characters which I have used occur uniformly in series 

 from the same flowers, except in the case of widely separated local- 

 ities, where they are still uniform for a given flower in a given locality. 

 There will be very rarely an individual proper to one flower found 

 on another, as one or two helianthi on Verhesina, but such excep- 

 tions do not vitiate the general rule. Some characters, as the differ- 

 ence in clypeal markings, belong especially to no one of these series, 

 and hence have no specific value. 



If, as believed, evolution is in progress among the species of Per- 

 dita, we are naturally led to seek for evidence of natural selection. 

 In some cases, as of the yellow lideola, heata and marcialis, all on 

 yellow flowers, we note at once the utility of the peculiarity ; and 

 when we see the yellow predaceous bug Phymata also on the flow- 



