186 BULLETIN 15 7, U. S. NATIONAL MUSEUM 



According to this interpretation P. g. canadensis represents the 

 species exclusivelj^ in Canada, but south of Canada occurs only as 

 a spring form. 



Comparable cases are found in Pafilio philenor^ which early in 

 spring in the District is represented by the western P. p. Mrsutus; 

 in Argynnis aphrodite cipris, which occurs in the West as a definite 

 geographical race and in eastern Massachusetts as a form of the 

 local A. a. aphrodite; and in Papil'io troilus, in which the south- 

 eastern race, P. t. ilioneus, occasionally appears in the District late 

 in summer apparently as a variant of the local P. t. troilus. 



All the early-spring specimens of Papilio glaucus referable to or 

 approaching Papilio glaucus canadensis that I have seen have been 

 males, the first females to appear being intermediates. In this con- 

 nection it may be mentioned that in P. g. canadensis as it is found 

 in Canada the males outnumber the females about 40 to 1, on the 

 basis of figures derived from general collecting, while in the southern 

 glaucus in summer the males outnumber the females less than 3 to 1. 

 So it is perhaps not surprising that toward the southern limit of its 

 range in the form canadensis the females wholly disappear. 



The local males of the canadensis type are very fond of congre- 

 gating on mud just as they are in the north. But after the appear- 

 ance of females and of intermediate males this species seems to give 

 up the mud-frequenting habit until the appearance of the second 

 brood in midsummer. More observations on this point, however, are 

 needed. 



Comparisons. — In eastern Massachusetts in the vicinity of Boston 

 the local summer form of the yellow swallowtail is intermediate 

 between the southern {glaucus) and the northern {canadensis) type. 



The males (pi. 34, figs. 1, 2) are light clear yellow, and are of the 

 same size as the great majority of the males from the vicinity of 

 Washington (pi. 33, figs. 1, 2), being therefore larger than the males 

 of typical canadensis. The black markings show the same range of 

 variation as in the local males, and the submarginal yellow spots 

 seem to be the same. Though generally speaking the black border on 

 the hind wings is of about the same width in specimens from Boston 

 and from Washington, it is occasionally much narrowed in the former 

 and much broadened in the latter. There is a slight average differ- 

 ence in the amount of blue scaling in the black margin of the hind 

 wings, this being more developed in southern specimens. Some 

 individuals from both localities have hazy and indefinite blue areas 

 in every interspace between the marginal lunule and the yellow discal 

 area, the one nearest the anal ocellus and above the orange lunule 

 being the largest, more densely scaled in southern than in northern 

 examples, the next two of rapidly decreasing size, and the remainder 

 vestigial except for that within the orange anterior lunule, which is 



