486 
NATURAL HISTORY OF AFRICA. 
Africa, particularly Guinea. It insinuates itself 
under the skin of the human species, principally 
of the arms and legs, and there it attains the 
length of ten feet. It is said that it will remain 
there for several years without producing any 
disagreeable symptoms ; but it sometimes occa- 
sions violent pains, and even convulsion, accord- 
ing to the part of the body it attacks. When it 
begins to protrude itself, great care must be em- 
ployed in extracting it, as it is very apt to tear 
and leave a portion behind, which occasions vio- 
lent and disagreeable symptoms. The operation 
of extraction is one of some time. 
The Physaliay or Portuguese sailor, met with 
in the tropical seas, and on the coasts of Africa, 
is often seen sailing on the surface of the ocean, 
by means of a particular organ which it uses as a 
sail, and hence is named by the French le petite 
galerey and by English mariners the Portuguese 
sailor. 
The red coral (Corallium ruhrum, Cuvier), so 
well known as an article of trade, is fished up on 
the coasts of Tunis, and in the waters of the Red 
Sea. It grows much slower than the madrepores, 
and never occurs in such masses. It is found at 
different depths ; and it is remarked, that light 
exerts a powerful influence on its growth. Thus, 
at a depth of from three to ten fathoms, it grows 
one foot in eight years j at the depth of from ten 
