COLOR PATTERN OF ELYTRA. 



79 



are fused posteriorly or anteriorly, respectively. Union at other than the 

 anterior or posterior ends is indicated by formulae like sc. a. + sc. p. /, which 

 shows fusion at the first transverse band. 



This table shows a most decided race tendency in each species in the 

 frequency of certain variations. Thus, in undecimlineata, almost no stripes 

 are wanting, the anal stripe being absent in only o. i per cent of the cases ; 

 but in multiUeniata, deccmlineata, and juncta is found an increasing tendency 

 for stripes to be missing, until in juncta and dejecta a maximum is reached. 

 In the various types of fusion also we find the same racial tendency for a 

 particular variation to increase or decrease as we follow it through a group 

 of species. These racial tendencies are of importance in geographical varia- 

 tion and species modification, which we shall discuss in the latter part of 

 this chapter. 



Variation in the proportion between the pigmented and tmpigmented areas in 

 the elytra of tlie lineata group. The variation in the proportion existing 

 between the light and dark color of the elytra of the group is significant, 

 indicating, as it does, racial tendencies or trends of variation. These ten- 

 dencies have been studied by seriations along a scale of values in which o 

 indicates total albinism or xanthism, or complete absence of dark color, 

 and 20 a uniform black or dark color over the whole elytral surface. The 

 data derived from this source is presented in the form of a table giving the 

 frequency which each species shows in any given class. 



Table 24. Variation in the proportion of light to dark color in the elytra of L. unde- 

 cimlineata, L. signaticollis, L. diversa, L. multitaniata, L. rubicunda, L. oblongata, 

 L. decemlineata, L. juncta, and L. defecta. 



