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Show 852 MR. W. BATESON ON THE [Dec. 3, colour, it is necessary first to sort them in respect of sex. This can be done without much difficulty. Besides a slight difference in shape and in sculpture (which gives to the elytra of the female a duller lustre) there is a well-marked depression or pit in the last uncovered abdominal plate of the male, while in the female there is no such depression. In attempting to arrange or group the specimens according to colour confusion is caused by the fact that variation occurs in several distinct features. Of these the three most noticeable are: (1) The ground-colour of the elytra. (2) The distribution of black pigment on the elytra. (3) The colour of the legs and underside of the body. Since the variations of the first two points are largely independent, it is not possible to exhibit the relationships and frequencies of all the variations by arranging the specimens in one series. The whole number, males and females, can, however, be seen to consist of two chief kinds-the one distinguished by having four black spots on the elytra (figs. 1-6, &c.) and a dark, generally black, underside to the body, while the other has an appearance of black striping on the elytra (figs. 20-23) associated with a light testaceous underside to the body. Those with undersides that cannot at once be referred to either the dark or to the light division are rare ; in the Tables given they are included under the heading " unconformable." In those with light undersides the legs are of a similar testaceous colour. If the underside is black, the femora are generally black too; but frequently the coxas and tarsi, and less often the tibias, are of a lighter colour. Examined closely the distinction between the distribution of the spots and the stripes is seen to be as follows:-The striping consists of pigment deposited in certain positions that can be defined pretty accurately by reference to the punctulations. These are somewhat more regularly disposed in the female than in the male, but by standing back to the light and looking at the specimen from behind it can be seen that the following arrangement is fairly constant. Following a line across the middle of an elytron there is next to the suture a double row of punctulations. External to this is an interval. Then come the 2nd-8th double rows of punctulations separated by intervals. Outside the eighth interval is a 9th row of punctulations, which is irregularly treble. It is in the four intervals between the 2nd and 3rd, 4tli and 5th, 6th and 7th, 8th and 9th double rows that the four chief trachea? of the elytron run; but the four principal stripes of pigment are placed in the other intervals, viz., between the 1st and 2nd, 3rd and 4th, 5th and 6th, 7th and 8th double rows of punctulations. There are not rarely a few dots of pigment in the other intervals, and, in the case of heavily striped specimens, these sometimes unite to form secondary stripes. The definite "spots," however, that are associated with the |
