78 Mil. A. MUURAT ON AN UNDESCBIBED 



read at the Meeting of tlie Britiah Association, at Dundee, in 

 1867. He says : — "At night the Fire- and Lanternflies were 

 magnificent. They exhibit, when at rest, only two pale-green 

 lights on each side of their head ; when excited or in motion, the 

 abdominal light shines bright, of a more reddish hue, and the 

 quicker they fly the brighter the light. A lovely Glowworm, too, 

 we saw, with similar lights, but smaller ; on being touched, a series 

 of minute sparks like pearls scintillated down its entire length in 

 two rows" (p. 21). 



The above accounts seem to show that the larva was full of 

 luminous matter, that the luminous matter was white, and 

 that it appeared red on the head from shining through the 

 chitinous texture, whereas its natural white light was seen when 

 the animal in its breathing or motion opened the port-holes of its 

 spiracles. That the light was not seen through the rest of the 

 surface of the body as through the head, would of course be due 

 to the greater thickness of the chitinous and muscular covex'ing. 



Now this general occupation of the body by the luminous matter 

 is the one point on which there is some coincidence witli the Fire- 

 fly. The light in the Glowworm is limited to the terminal seg- 

 ments of the abdomen ; in the Firefly, on the contrary, the light 

 occupies, besides the spots on the thorax, where they are most ob- 

 served, the whole interior of at least the middle of the body ; and 

 wherever there is a chink or joint the light streams through. This 

 is a fact noticed by every one who has observed them in their native 

 country. On bending the body and raising the elytra, a much 

 more intense light is seen to exist in the interior than in the two 

 spots on each side of the surface of the thorax. This is some- 

 times observed even while the insects are flying about, if the 

 position of the spectator is such that the underside of the body 

 is exposed to him. Then he sees a light much moi'e brilliant than 

 usual, appearing and disappearing with the motion and change of 

 position of the insect. 



I may here observe that the diffusion of the light throughout 

 the whole body, as in this new larva, is a phenomenon more easy 

 of comprehension than is its limitation to the terminal segments 

 of the abdomen as in the Glowworm, or to the nasal projection as 

 in the Fulgora (always supposing the reported luminosity of that 

 organ in them to be really true). It appears to me that the phe- 

 nomenon in all these insects' is one of chemical action, and that 

 the chemical action is that of oxidization produced by respira- 



