1895.] COLOTJB-VABIATIONS OF A BEETLE. 853 



black undersides (as in fig. 1, &c.) consist of patches of pigment " 

 usually placed so as to cross respectively the one the 2nd, 3rd, 

 and 4th, the other the 7th and 8th double rows of punctulations. 

 The extent of these spots varies greatly and in its condition of 

 least development the central of the two spots coincides very 

 nearly with the 3rd double row of punctulations, and the lateral 

 spot similarly is very nearly on the 7th double row. 



All these arrangements are liable to irregularity, but in the 

 main they are as described, and essentially in the spotted form 

 pigment crosses certain of the double rows of punctulations, while 

 in the striped form it is almost entirely in the inte^-vals between 

 them. 



The association of the black spots on the elytra with a dark 

 underside is exceedingly close, and it scarcely ever happens that a 

 specimen which has black pigment in the position of the spots 

 (fig. 1) has a light underside. This principle is obeyed whatever 

 the ground-colour of the elytra may be. Figs. 25 and 26, 28-30 

 are given as illustrations of specimens in which the rule is not 

 followed, the undersides not being black though there is black 

 pigment on the elytra in the situation of the spots. 



This division into spotted forms with dark undersides and 

 striped forms with light undersides is the most conspicuous feature 

 in the variation of the insect. In great measure the distinction is 

 sexual, most of the males belonging to the spotted division and 

 most of the females to the striped. Curiously the number of each 

 sex which belongs to the opposite group is about the same, for on 

 sorting it appears that 



Of males about 80 per cent, are of the spotted class. 



» „ 18 „ „ striped „ 



Oi females „ 25 „ „ spotted „ 



„ ,, 71 „ „ striped „ 



This reckoning is made without reference to ground-colour, and 

 specimens that have striping as well as spots are of course included 

 in the spotted class, to whicti they belong also by reason of their 

 dark undersides. 



Of the spotted form the great majority (73 per cent, of all 

 males and 19'6 per cent, of all females) have red as the ground-colour 

 of the elytra. Of the striped form, on the other hand, the majority 

 (19 per cent, of all males and 65*7 per cent, of all females) have 

 greenish grey as the ground-colour. In fact the great majority of 

 males agree pretty closely with fig. 1, while the great majority of 

 females resemble fig. 13 ; but of the males the need commonest 

 form is that shown in fig. 13, and of females the second commonest 

 is that of fig. 1. It thus appears that the form which may be 

 called normal for the female is the commonest variety in the male, 

 and the converse is true though to a less degree. 



The thorax of the striped forms usually has black pigment as 



