290 WILLIAM LAWRENCE TOWER. 



choosing these three species was that any two of them, when 

 crossed, give only certain very definite and invariable products, 

 and I was thus enabled to eliminate many complications and pos- 

 sible sources of error. The contrasting characters are as follows : 

 Between L. signaticollis Stal (Fig. i) and L. undecimlineata 

 Stal (Fig. 2), in the adult, the elytra of L. undecimlineata have 

 deep greenish black longitudinal stripes, edged with a double row 

 of punctations, while L. signaticollis has the punctations, but 

 not the stripes. The ground color of the elytra in L. signaticollis 

 is grayish, while in L. undecimlineata it is white. No other 

 characters in the adult had sufficient contrast to give sharp al- 

 ternative inheritance. The larvae of the two are sharply con- 

 trasted ; those of L. undecimlineata and L. signaticollis are exactly 



H C 



Fig. I. L. signaticollis Stal. (A) Adult. Showing the absence of pigmenc, 

 and the presence of the impressed punctations on the elytra which border the stripes 

 in other species. The absence of pigment may well represent the negative half of 

 a Mendehan allelomorph. {B) Full-grown larva. Showing the arrangement of 

 black color marks upon the sides and back of the larvae. The ground color in 

 this state is bright chrome yellow. ( C) Larva of second stage. Showing the char- 

 acteristic color pattern. The ground color is a light chrome yellow. 



alike in the first stage, but in the second stage L. undecimlineata 

 is white and L. signaticollis yellow, both with the same system 

 of spots, and in the third stage L. signaticollis is yellow with 

 well-developed tergal stripes and L. undecimlineata is pure white 

 without stripes. These differences are well shown in text Figs. 

 I and 2. 



In L. diversa (Fig. 3) the elytra are marked by longitudinal 

 stripes of greenish black edged with an irregular double row of 

 punctations, and the larvae are in all stages exactly like those of 



