116 Beautiful Shells. 
closed in a fine skin or mantle. The mouth is 
placed at the lower part, near the opening, whence 
the cirrhi issue forth ; this mouth is a curious piece 
of mechanism, being furnished with a horny lip 
covered with minute palpi, or feelers; there are 
three pairs of mandibles, that is jaws, the two outer 
ones being horny and serrated, that is jagged or 
toothed like a saw; the inner one is soft and 
membranous, that is, composed of little fibres, like 
strings, crossing each other, as we see what are 
called the veins in a leaf. 
Much more might be said about the internal 
structure of the Cirrhopods, or Balani, as the 
Barnacle group is sometimes called, from the Latin 
Balanus—a kind of acorn. By some naturalists, 
the term is not applied to the stalked Cirrhipoda, 
like that we have been describing, but only to the 
sessile kinds, that is, those which set close or grow 
low ; from the same Latin root comes the English 
word session—a settling. The coverings of these 
Dwarf Barnacles are sometimes called acorn shells; 
they are commonly white, of an irregular cone 
shape, composed of several ribbed pieces, closely 
fitted together with an opening at the top, closed 
by an operculum, or stopper. 
These shells cover in patches the surface of 
