312 



The Mechanism of Evolution in Leptinotarsa 



41 83 



697 Males, 



Total 1535. 838 Females. 



Fig. 119. — First census at Tlerra Blanca in 1907 showing condition in the popu- 

 lation with regard to pronotal pattern. 



34 91 



438 Males. 



4--^ 

 81— 



43 



l# 



—103 

 ^^\Cit"219 



29 87 



Total 1059. 621 Females. 



Fig. 120. — Second census at Tlerra Blanca in 1907, showing condition In pro- 

 notal pattern. 



'"S::"-^^^^ 194 



^%iM;:^^p 318 



/ / / ^^r---i47 

 / / ' 



i/i/ 



/ 



7m- 

 \ 



92 

 946 Males. 



56 



Total 1973. 



1^ 

 44 13 51 7 



1027 Females. 



Fig. 121.— First census at Tierra Blanca In 1908, showing sudden Increase In 

 certain directions in pronotal pattern and the sudden rise of three strongly 

 developed isolated blotyplc groups in both sexes. 



41— 



<t^%, 





14 91 58 



1231 Males. 



Total 2141. 910 Females. 



Fig. 122. — Second census at Tlerra Blanca in 1908, showing condition in the 

 population as a whole and the persistence of isolated groups in previous censuses. 



