278 ENTOMOLOGICAL NEWS [June, '13 



color tone is diagnostic, a condition where some absolutely 

 fixed standard is imperative, the absence of which has been a 

 fruitful source of misunderstanding and ambiguity. With 

 the student of color variation and protective coloration the 

 need of an exact system of expressing color value has been 

 just as decided and the appearance of Mr. Ridgway's "Stan- 

 dards" should receive from all entomologists the attention it 

 so fully deserves. 



The method of treatment is thoroughly scientific and the 

 values are obtained by mathematically determined mixtures. 

 The thirty-six principal hues are based on the solar spectrum, 

 each hue being graded in a vertical scale with fixed proportions 

 of white and black. The same set of color tones are repeated 

 with increasing admixtures of neutral gray, first with thirty- 

 two per cent., second with fifty-eight per cent., third with 

 seventy-seven per cent., and fourth with ninety per cent. By 

 a very simple method of notation it is very easy to follow a 

 single hue and its numerous tones through all the steps from 

 purity to greatest paleness on the one hand and to the point of 

 greatest divergence in neutralization on the other. This is a 

 very important matter to the student who is dealing with 

 recessive and intensive color patterns, the exact tone of which 

 is far harder to express than the form of the pattern itself, 

 in fact practically impossible to definitely express without a 

 system similar to that employed by Mr. Ridgway. 



The technique of the work is excellent, each of the eleven 

 hundred and fifteen tones having been colored in large sheets 

 at one time with the same mixture of pigment to insure abso- 

 lute uniformity, the sheets being cut up and the squares placed 

 in their respective positions on the plates. 



Entomologists can rejoice with their ornithological breth- 

 ren in the appearance of this noteworthy and epoch-making 

 work, which is a monument to the industry and persistence of 

 the author. The utilization of these color terms will simplify 

 the perplexities of modern color descriptions and once used the 

 value of the "Standards" will be fully recognized. 



J. A. G. R. 



