1895] ENTOMOLOGICAL NEWS. 61 



chrasti covers the whole of the dorsum of the third segment, is 

 \n prunotincta shifted backwards, so as to have its upper margin 

 on the fourth segment. 



In stcmichrasti the yellow bordering the second segment be- 

 comes deeper, almost orange, in tone, and much greater in extent; 

 while the small intrusion into the black mentioned in pmnotiruta 

 becomes in sumichrasti a large, clean-cut notch in the black mid- 

 dorsum of the segment. Here again we see the markings of 

 sumichrasti shifted backward in prunotincta, and the same is the 

 case as above explained, also on the thor.ix. 



Comparing dugesii, prunotincta and sumichrasti, one sees that 

 in spite of great superficial differences of color they are nearly 

 related ; and on further reflection, there appear good reasons 

 for regarding dugesii as furthest from, and primoiincta nearest to 

 their common ancestor. It may not be out of place to dwell a 

 little on this phase of the subject, and so depart from the usual 

 dry detail of descriptive entomology ! 



In prunotincta and su??iichrasti we find yellow hairs, but none 

 scarlet. In dugesii beautiful pinkish scarlet hairs appear on the 

 abdomen, while in the little heterchroa they have extended to the 

 head and thorax. In all groups of animals, it is recognized that 

 yellow and yellow colors are intimately related, and that red is a 

 later product of metabolism than yellow ; thus red forms vary to 

 yellow, but not yellow to red, except in the form of gradual red 

 suffusion. Red varying suddenly to yellow is regarded as ata- 

 vism; thus, for example, the red Lopidea media has a yellow 

 variety, robiniee Uhler, which we hold to be either ancestral or 

 atavistic in its nature. 



It follows, therefore, that we have presumptive evidence for 

 regarding sumichrasti as an older type than dugesii, and dugesii 

 as older than heterchroa. On examining the maculation we find, 

 as above stated, that the markings of sumichrasti are thrown 

 about a segment backwards in prunotincta. But in dugesii, 

 compared with sumichrasti, they appear to be slightly thrown 

 forwards, so that, for example, the black spot of the apical half 

 of the abdomen intrudes on the second segment, and the black 

 proper to the second segment is pushed to its base. Consequently, 

 as sumichrasti falls, in regard to its maculation, between dugesii 

 and prunotincta, and as we have held dugesii to be a later type 



