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marine animal luminosity, the Cuttles and Squids are slightly 
light-emitting on their outer surface. 
I am not aware of any fresh-water invertebrate which possesses 
the gift, and the statement that Infusoria are occasionally 
luminous does not appear to be founded on satisfactory evidence. 
On land, certain Myriopoda give out a sparkling light, re- 
sulting from muscular contraction ; and there is a remarkable 
slug found in Teneriffe, Limax or Phosphorax noctilucus , 
which has a luminous pore in the posterior border of the mantle. 
Many insects have little tiny spots on them which emit light, 
and it would appear that the localization of the minute pheno- 
menon is in relation with wax glands. On the other hand, the 
great- headed Fulgora or lantern-fly is said by some naturalists 
to glow with red and white all about the forepart, and by other 
observers to do nothing of the kind. 
The great display is produced by some species of two families 
of beetles, the Lampyridce and Elateridce , and the glowworm is 
one of the former. Belonging to the genus Lampyris , it is in 
classification, in the neighbourhood of the family Telephoridce , 
and its close ally is the genus Drilus , in which great disparity be- 
tween the sexes is not accompanied by luminous phenomena. 
Lampyris and Drilus lead the same kind of lives, and in the 
larval state are carnivorous, preying on snails, whose body they 
devour during life. As every work on Entomology has descrip- 
tions of species of Lampyris , it is only necessary to group the 
gifts of all, in the following remarks. The large yellow egg is 
even luminous on first leaving the body of the female. It is stuck 
on to moss, low grass, or even earth by a viscid fluid ; and when it is 
hatched the long-narrow flat larva soon begins its cruel life, and 
has an apparatus for brushing off the slime of its victim. It 
attains its full size in warm Aprils, and some turn to the pupa 
condition in the summer; but usually the larva lives on, hyber- 
nates in the winter, and turns to the pupa in the spring. The 
larva has photogenic organs on the antepenultimate segment of 
the body (PI. VI. fig. 9) ; they are on its under surface, one on 
each side of the middle line, and are like small sacs in shape. 
Overlapped more or less by the segment in front, they become 
visible when the insect extends its abdomen, and then they are 
noticed to be luminous. On the other hand, when the body is 
retracted they are hidden, and the light is not seen. Under 
all circumstances the light is excessively feeble. 
When about to undergo the first metamorphosis, this larva 
becomes quiescent, and after skin-shedding, a pupa is presented — • 
not a quiet one, however, for it has the power of moving the 
antennae, head, and legs, and of twisting its body about and 
pushing itself along by the alternate contraction and expansion 
of the abdomen. The female pupa is without wings, but the 
