112 CAROLINE BURLING THOMPSON 



headed larvae.' He describes the eye of an 'indifferent larva' 

 as a mass of undifferentiated cells, which later will differentiate 

 into two layers of small outer cells and larger inner cells. He 

 then describes and figures (figs. 11, 12) two sections from the 

 eye of a small headed nymph with twelve antennary segments, 

 which he evidently considers typical for all nymphs with this 

 number of segments. On the contrary, the eye shown in v. 

 Rosen's figures 11 and 12, is undoubtedly that of a reproductive 

 type, and quite different from the eye of the worker-soldier type 

 of the same age, which he has not recognized, v. Rosen's 

 figure 13, a section of the eye of a 'small headed larva' with 

 fourteen to fifteen antennary segments, is, of course, that of a 

 reproductive type; his figure 14, from a 'large headed larva' 

 with fourteen to fifteen antennary segments, is a typical worker- 

 soldier type of eye. 



I must repeat once more that, in L. fiavipes, both types of 

 eye are found from the beginning, side by side in the reproductive 

 and worker-soldier types of the recently hatched nymphs, and 

 it is probable that the same is true of L. lucifugus. 



The reproductive organs of both sexes are distinguishable at 

 the time of hatching and differ in size in the two types of newly 

 hatched nymphs. This size difference is especially noticeable 

 in the females, but it is also true of the males (figs. 24 to 27). 



Grassi states that in L. lucifugus "there is no trace of the 

 external genitalia, which do not become evident until the larvae 

 are divisible by the greater or less size of the heads;" by 'ex- 

 ternal genitalia' evidently meaning the pair of cerci on the 

 median line of the posterior edge of the ninth abdominal sternite. 

 In L. fiavipes and L. virginicus these cerci, as well as the more 

 laterally placed pair on the tenth segment, are present in all 

 nymphs at the time of hatching. 



In the newly hatched reproductive type the ovaries are about 

 one-third larger in general bu k than in the worker-soldier type. 

 The oviduct is large and conspicuous, the ovarian tubules are 

 long and numerous, and the egg cells are large (fig. 24). All 

 of these characters are diminished in the worker-soldier ovaries. 

 The oviduct is smaller, the ovarian tubules are fewer and shorter. 



