LUMINOUS ANIMALS 
149 
a bluish light from all over its body, and the 
scale-back (Polynoe) gives forth a greenish 
light where the elytra or scales upon the back 
join the body. 
Yet another light-bearer is the phosphores¬ 
cent sea-pen (Pennatula phosphorea), found 
in the Mediterranean and the Atlantic. This 
curious creature grows to a foot or more in 
length, and consists of what may roughly be 
termed a main stem from the upper part of 
which arise leaf-like appendages. The lower 
portion of the stem is somewhat like an elon¬ 
gated onion in form, and the general outline 
of the creature suggests a closed feather-fan. 
When disturbed it emits flashes of light, the 
intensity of which varies according to the 
amount of irritation to which it is subjected. 
Not a few of the centipedes are of a luminous 
nature, the creatures producing light by the 
agency of a phosphorescent fluid yielded by 
glands opening upon the body. 
One of the best known of the luminous 
animals found in this country is the glow¬ 
worm, a creature that, in spite of its name, 
is not a worm but a beetle. The sexes differ 
considerably the one from the other, the 
male possessing wings and the female being 
without those members. 
Indeed, so greatly do the latter resemble 
