219 



The details previously given are collated in the following- 

 table, in which the figures, when standing alone, represent per- 

 centages of individuals of the variety with bluish to yellowish 

 tibiae, instead of red. Estimated percentages are queried, and 

 dashes indicate lack of data or non-occurrence of species. In 

 the absence of precise data the proportion is expressed by words, 

 or, if unknown, is indicated by the plus mark ( + ). 



DISTRIBUTION AND PROPORTION OF MELANOPLUS HAVING BLUISH TO YELLOWISH HIND TIBLjE 



The variation in tibial color has no marked relation to sex. 

 In the small series of.il/. minor at hand the tibiae are bluish, or 

 in the female sometimes red; in M. angustipennis from Wauke- 

 gan two of every three males have red tibia? (21 of 33), and two 

 of every three females have them bluish (20 of 31). 



This tibial variation belongs to what Bateson calls discon- 

 tinuous variation, the transition from red to bluish in a series 

 of specimens being more or less sudden. Specimens at the 

 point of change show one color basally and the other apically. 

 This variation is attributed by Cockerell ('89) to an influence 

 promoting or arresting a metabolism of pigment. The order of 



