90 THE CANADIAN ENTOMOLOGIST. 



lacking, a rather broad gap between sections 4 and 3 would result. 

 Even in that case, the systematic unity of pattern would remain evident. 

 Section 5 accords entirely in system with section 6, yet it happens that 

 actual intergrades between them are extremely scarce, so that these two 

 bodies of variation are also nearly isolated from each other. The only 

 intermediates between sections 5 and 6 are figures 8 and 4 and a single 

 additional specimen ; all three are bred specimens — " missing links " are 

 not always so easily obtained. 



Sections 5 and 4 are not visibly harmonic. Between them exists a 

 break of continuity by lack of intergrades, and this break resembles a 

 systematic partition, from the fact that the methods of pattern growth in 

 the two series appear discordant. Although the section 5 pattern is more 

 like formal Petrosa than is the pattern of section 4, yet a higher stage of 

 the method of section 4 reaches practically the Petrosa pattern without 

 in transit assuming the section s pattern, or so it seems. It is a fact thai 

 section 5 shows more plainly its alliance with sections 2 and 3 than with 

 section 4, while section 4 more clearly manifests its alliance with section 

 6 than v/ith section 5. Yet sections 4 and 5 undoubtedly belong in the 

 relative positions mentioned. Study of the males alone does not relieve 

 this apparent discord. The males matured indoor from estray pupae, or 

 from larvae found wild and fed up, have not supplied any examples 

 reconciling this lack of harmony. I have bred two considerable families 

 from eggs, but it has singularly occurred in each instance that all the 

 resulting males belong on the " Petrosa " side of this gap. Figs. 1 1 and 

 16 were from one lot of eggs, and although they are a good distance 

 apart as to pattern advancement, yet they are plainly identical in method, 

 fig. II being intergraded with fig. 16 by figs. S and 4, as also by section 

 5 and by some other specimens. Study of the females supplies con- 

 vincing evidence that this apparent lack of harmony at one point in the 

 series of flown males is not due to a systematic partition. In the series 

 of females no corresponding discord is foimd. Also, we have in figures 

 12 and 17 direct evidence uniting the extremes of the general series. 

 These two females were bred from the same lot of eggs which produced 

 figs. II and 16. Fig. 12 is almost normal Petrosa. Fig. 17 may safely 

 be considered a very moderate divergence from formal Scudderi. These 

 two females efficiently unite the extreme terms of the series. The lack 

 of unity between sections 4 and 5 is due mainly to the fact that there is a 

 meagerness of representation at that part of the series of males. The 



