COLOR PATTERN OF PRONOTUM. 7 1 



member of the genus, is black or deep brown, appearing black by reflected 

 light, and is almost invariable in color. L. hogei has the thorax dark brown 

 with a greenish iridescence, which in the few specimens at hand appears to be 

 slightly variable toward a stronger development of the metallic-green portion 

 of the coloration. The species haldcmani , libatrix, and violescens present a 

 series of color variations from black to deep metallic-blue, a range which 

 may be divided into the following classes: (i) Black, (2) polished black. 

 (3) black with faint blue iridescence, (4) light metallic blue-black, (5) 

 metallic blue-black, (6) deep blue-black, (7) violet. In the following table 

 is given the frequency of the variations seen in the different species : 



Table 16. Variation in the color of the pronotum in L. haldemani, 

 L. libatrix, and L. violescens. 



L. haldemani : N. = 200 individuals. Mean of classes = 1.68. 

 L. libatrix: N.= 100 individuals. Mean of classes = 4.o8. 

 L. violescens : N. = 100 individuals. Mean of classes = 6.87. 



No other lines of color variation in the pronotum of this group are known 

 to me. However, some of the species of this group I have not had an oppor- 

 tunity to examine. The variability of the three species studied is low, a fact 

 plainly indicated by the high percentage of variates in the modal class, and, 

 like the preceding groups, is limited to two directions. 



Variation in the color of the pronotum i?i the other groups. In the lacerata 

 group, as far as is known from the specimens available, the individual varia- 

 tion of the pronotum is extremely slight. In the rubiginosa and zetterstedti 

 groups the species are constant, presenting only the slightest oscillations, too 

 slight to be measured with any degree of success, while in the flavopustulata 

 group, as far as I know, the color of the pronotum is invariable. 



The study of the individual variation of the color and color pattern of the 

 pronotum warrants the following conclusions : 



(1) Variatiofi is definite in opposite directions. 



(2) No trace of indeterminate variation exists anywhere. 



(3) The variations follow exactly Quetelet's law. 



