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THE CANADIAN ENTOMOLOGIST. 



graduated to fifths of millimeters. By use of a lens these divisions coulJ 

 easily be divided to fourths, that is, to twentieths of a millimeter, so that 

 the error in any case should have been within half this amount, or less 

 than 0.025 mm. The captured specimen was taken from the middle of 

 the series, in order to obviate any error due to a fall of temperature while 

 the observations were being made. Sixteen such series were recorded, 

 and consequently sixteen wing measurements were made. The results of 

 these measurements are given in Table III. The quantities in the fifih 

 column are found by dividing those in the third column by those in the 

 fourth. 



Table III. — Showing the length of wing of individuals of CEcanthin 

 niveus, the rates of chirping of these individuals, and the average rates of 

 other individuals at the same time : 



If, now the wing-lengths and the ratios of the individual rates to 

 the average rates be plotted as ordinates and abscissae, respectively, they 

 should group themselves in some noticeable fashion about an oblique line, 

 provided there is any correlation between wing-length and rate of 

 stridulatioM. B it no such grouping is apparent (fig. 14). Particularly 



