4 upon 'Luminous Animals. 279 
naria. The light in this genus has been observed to issue 
from the remarkable proboscis on the fore part of the head. 
This part has always been described by authors, as hollow or 
empty, which I have found to be perfectly correct ; and what 
is more extraordinary, that the cavity communicates freely 
with the external air, by means of a chink or narrow aperture, 
placed on each side of the root of the proboscis. This pro- 
jection is covered internally by a membrane, between which 
and the horny part or shell, there appears to be interposed a 
pale reddish coloured soft substance, that is arranged in the 
candelaria in broad lines or stripes ; but it is so thin, that I 
could not distinctly examine its structure, or absolutely deter- 
mine, whether it should be considered as a substance intended 
to furnish the light of these insects, or the pigment upon 
which the colour of the proboscis depends. 
The globes of the antennae constitute the organs of light 
in the pausus spherocerus. Dr. Afzelius, who discovered the 
luminous property in this species, compares them to lanterns 
spreading a dim phosphoric light.* The rarity of the insect 
put it out of my power to examine its structure, but from the 
form and situation of its organs of light, it is most probable 
they are constructed like those of the fulgorae. 
It has been conjectured by Carradori and others, that the 
lampyrides were enabled to moderate or extinguish their light, 
by retracting the luminous substance under a membrane ; but 
neither in them, or any of the other luminous insects, have I 
found an apparatus of this sort. The substance furnishing the 
light, is uniformly applied to corresponding transparent parts 
of the shell of the insect from whence it is not moved; indeed a 
* Lin. Trans. Vol. IV. 
O O 2 
