278 KELLOGG AND BELL 



light of this interpretation of the variation conditions of soror it 

 would be of much interest if we could know the exact (as de- 

 termined by statistical study) conditions of the species at the 

 time soror was originally described. Was the 12 -free-spots- 

 condition really the dominant mode then? Or did the original 

 describer simply have a few specimens in hand, all of which 

 happened to be of this type? Fortunately we are able to pre- 

 sent the statistical facts of this color pattern variation in a series 

 of 906 individuals of soror collected on the Stanford University 

 campus in 1895 (a collections lot found by us in rummaging 

 through the old unworked material in the department's cabinets). 

 The characteristic color-pattern variations in this lot are the same 

 as in the 1901 and 1902 lots, with the following frequencies : 



Class A : 383 individuals with all twelve spots separate (the 

 mode). Class B : 55 individuals with left middle pair confluent. 

 Class C : 64 individuals with right middle pair confluent. Class 

 D : 203 individuals with both middle pairs confluent. Class E : 

 ii individuals with left posterior pair confluent. Class F: 8 

 individuals with right posterior pair confluent. Class G : 26 

 individuals with both posterior pairs confluent. Class X : 47 

 individuals with both middle and posterior pairs of both sides 

 confluent. Class H : 108 individuals showing longitudinal con- 

 fluence on one or both sides. 



The polygon showing these frequencies graphically is as 

 shown on next page. 



Thus in 1895, seven years ago, soror in the same locality, 

 showed a dominant pattern of twelve free spots on the elytra 

 (fig. 50 A), as originally described for the species. But the 

 pattern second in point of frequency was that which to-day is 

 the dominant one in the species (fig. 50 B> C). The percentages 

 of these two patterns in the three series collected in 1895, 1901 

 and 1902 from same locality are : 



With all spots free: 42.35 per cent, in series of 1895, 34.5 

 per cent, in series of 1901, 34.5 per cent, in series of 1902. 



With spots of middle pairs fused : 22.4 per cent, in series of 

 1895, 43.7 per cent, in series of 1901, 42.8 per cent, in series 

 of 1902. 



The new species of Diabrotica, splitting away from D. soror 



