PHOTOGENIC ORGANS OF LAMPYRIDS 181 



the Lepidoptera and Hymenoptera, according to Korschelt and 

 Heider ('99) the limb rudiments of the first abdominal segments 

 are, in some cases less developed than those of the other seg- 

 ments, and in no case do they attain a greater development. 

 According to Graber, they are most leg-like in Mantis and 

 developed into very large vascular sacs in Melolontha. In other 

 cases they are mushroom-shaped, stalked cups, or they may be 

 sunk below the surface of the body, i.e., invaginated (Hemiptera). 

 (Dr. Wheeler thinks that the immersed condition of the hemip- 

 terous pleuropodia represents a late stage where such a condition 

 is to be expected.) 



The pleuropodia have been regarded as transitory respiratory, 

 sensory, supporting, and glandular structures. The last view 

 though indefinite, appears the most logical, since in most in- 

 stances they are distinctly glandular in character. Wheeler 

 thinks that the pleuropodia in ancestral insects may have func- 

 tioned as odoriferous glands. Since they are so well developed 

 in many cases, it is reasonable to suppose that they must be 

 of some importance. In Photuris and Photinus embryos, stained 

 in toto with borax carmine, the pleuropodia took the stain more 

 deeply than the general body wall and more conspicuously than 

 the other appendages, thus showing the more permeable char- 

 acter of their membrane. 



SUMMARY 



1. The two species of fireflies, Photinus consanguineus and 

 Photuris pennsylvanica, differ in habitat, manner of flying and 

 of scintillating, as well as in the color of the light emitted. The 

 males and the females each scintillate in their own peculiar 

 manner. 



2. Both species require two seasons to complete their meta- 

 morphosis, the larval life occupying the far greater part of this 

 time. They hibernate under stones and in the soil as young and 

 as nearly full-grown larvae. The uniformity of a brood may be 

 broken by the varying rate of growth of the individuals. 



3. The eggs of both species are subspherical, and at first sticky, 

 and are laid among roots or just under the soil. In the labora- 



