14 BULLETIN 15 7, U. S. NATIONAL MUSEUM 



in early summer, especially at the beginning of the summer brood 

 in P. interrogationis. 



The two local species of Ghlorippe {C. clyton and C. celtis) both 

 occur in a lighter and a darker form. These two forms are very 

 distinct in C. clyton, but are only slightly marked in C. celtis. Both 

 forms fly together, and seem to have no relation to season or to 

 locality. 



In reviewing the District butterflies w^e are at once struck by the 

 fact that in no less than 12 species we find a distinctive form char- 

 acterized hy small size, pale or dull colors, especialh'^ a restriction of 

 black or dark markings and an enlargement of light areas, and un- 

 usual activit3\ There is a second intermediate form, and a third 

 large, richly colored, and relatively inactive form. The species in 

 which these three forms are well marked are Phyciodes tliaros, 

 Jwfwnia lavinia coenia, Pyrameis atalanta, Pyrameis cardui, Lycae- 

 nopsis argiolus pseudargiolus, Pieris protodlce, Pieris rapae, Golias 

 phUodice, Golias euinjtheme, Papilio philenor, Papilio glaucus, and 

 Papllio marcellus. 



In all these species, with the single exception of Golias eurytheiiie, 

 these forms occur in the same sequence, first the smallest and dullest, 

 then the intermediate, and lastly the largest and most richly colored. 

 In Golias eurytheme, which here is an intrusive species, this same 

 sequence is found in other regions. 



In Phyciodes tharos, Lycaenopsis argiolus pseudargiolv^, PieHs 

 protodice, P. rapae, Golias philodice, Papilio philenor, P, gloMcus, 

 and P. marcellios the small light form is normally confined to more 

 or fewer of the earlier individuals of the spring brood, the later 

 individuals of the same brood being of the intermediate form. 



In Junonia lavinia coenia, Pyrameis atalanta, and P. cardui all 

 the individuals of the brood which flies in spring are of this form. 

 In Pyrameis cardui, as it is found in the District, the early-summer 

 brood is made up of the intermediate and the richly colored form, 

 and the late-summer brood consists wholly of the latter. In Junonia 

 lavinia coenia and in Pyrameis atalanta the small dull form is joined 

 in summer by the intermediate form, and in late summer both forms 

 are joined by the dark, inactive form, all three forms flying together. 



In addition to the butterflies in which there are three well-marked 

 forms there are several others in which there are two distinct forms, 

 sometimes with traces of a third. In Glirysophanus phlaeas liypo- 

 phlaeas there is a well-marked early-spring form, and the first indi- 

 viduals of the second brood are not infrequently more or less inter- 

 mediate between this and the summer form. Papilio polyxenes 

 asterias does not fly until after the early-spring forms in the other 

 swallowtails have disappeared, so that an early-spring form is not 



