THE CANADIAN ENTOMOLOGIST. S\) 



Section 2 contains 16 intergrades very close to Sciidderi. Some are 

 like fig. I of the plate, some have the longitudinal stripe of f. vv. pro- 

 longed nearly to a junction with the oblique bar, a few have slightly 

 developed light markings on hind wing. In several examples the 

 oblique bar on f w. is largely produced, and on basal side projects a 

 branch backward toward the systematic point of junction with the longi- 

 tudinal stripe, although this stripe is only developed to the extent of a 

 short ba'-al spur. In section 3 are 20 intergrades near to Scudderi, but 

 having usually a well defined light pattern on h. w., as in figures 3 and 7 

 of the plate. Section' 4 comprises 7 very characteristic intergrades 

 nearer to Scudderi than to Petrosa. Fig. 5 stands for this section, and 

 is nearer than the rest of section 4 to the character shown in section 3. 

 The other 6 specimens in section 4 appear to form a progression in 

 pattern of h. w. away from fig. 5 in the direction of Petrosa (fig. 16). 

 This progress, however, does not consist of sharply defined gradations 

 like the h. w. pattern steps seen in figures 8 and 4, which figures so 

 normally lead toward fig. 16. In the progression formed by these 7 

 specimens, the h. w. black area, extending in fig. 5 from the central white 

 band to the base of the wing, becomes in the other specimens increasingly 

 indefinite and finally nebulous, as if the black were eliminated atom by 

 atom without any definite pattern evolution. In the 7th term of this pro- 

 gression, the h. w. is practically like that of fig. 2, except that the basai- 

 part of the wing, in addition to the two black streaks seen in fig. 2, has 

 also a slight haze of black scales. This 7th term, however, is not as to f. 

 w. a typical Petrosa, for the longitudinal stripe is extremely tenuous at its 

 end next the oblique bar. In the other 5 specimens the longitudinal 

 stripe is scarcely more developed than in fig. 5 of the plate. Section 5 

 has 10 intergrades, very uniform, decidedly nearer to Petrosa than to 

 Scudderi. They come between fig. 1 1 and fig. 8, but nearer the latter. 

 Section 6 is formal Petrosa, consisting of 41 specimens. Figures 2, 6 

 and 16 exemplify this section, fig. 16 being the dominant local form. In 

 section 6 variation is subordinate to a general equality or maturity of 

 pattern. 



Sections i, 2 and 3 are not in the slightest degree distinct in a 

 systematic sense. Together they number 50 individuals, constituting the 

 form Scudderi with its inseparable variations. Section 4 agrees in 

 system with the previous section, but between the two masses there is an 

 appearance of discontinuity. In case fig. 5 and another specimen were 



