Analysis of Heteeogeneity in the Population 289 



whether they were the product of an introduced individual of this biotype or not 

 is impossible to determine. The remainder of the population showed only the 

 customary array at this location in both sexes. The second generation in this 

 year showed biotype 1 in both males and females as widely isolated groups. The 

 remainder of the population was fairly well massed, but showed indications of 

 extending the range of pattern in several directions. The recorded conditions I 

 have also shown in figures 84 and 85. 



17 ^- 



14 «» 



19-1 - m- 



81—— ^ 42-— ^^^. ^ 



29 ^' -^~-. ,2 • 45- ^ J^-: 55- 



46 ^ ^ gg 51 ■ ^ j^ 61 



'^ it«t 77 ~,4M* ii^ 74 



/ ^ i^fy. ^'^ 33 /^M* iJvit 79 



/ \ *' / \m — « 



n 14 26 31 



462 Males. Total 970. 508 Females. 



Fio. 84. — Census of first annual generation at Tlalnepantla In 1906, showing 

 the array in pronotal pattern. In this generation there appears the introduction 

 (apparently) of biotype 1 in the pronotal pattern which was present only in the 

 males. 



12.1 



FiQ. 85. — Census of second annual generation at Tlalnepantla in 1906, showing 

 the presence of biotype 1 in both sexes and an increased array present in the gen- 

 eral mass of population. 



In the year 1907, the last at this location, the first generation showed no indi- 

 cations of isolated groups and only a much restricted range in the pattern, 

 nearly identical to that found in previous years. The census of the second 

 generation showed the usual well-defined and restricted mass, with little 

 tendency to diverge, and isolated groups of biotypes 1, 8, 10, and 12 in the males, 

 and of 1 and 8 in the females, all of which were fairly strong in numbers and 



