136 MOLLUSCA. 
which, in certain species, are nearly as large as the former 
(Lepas mitella); frequently there is an azygous valve oppo- 
site to the ordinary one of the same description. In the 
CINERAS, Leach, 
The cartilaginous mantle contains: but five small valves, 
which do not occupy the whole of its extent. (Cineras vit- 
tata, Leach.) 
Orion, Leach. 
The cartilaginous mantle contains but two very small valves, 
with three little grains that hardly merit that name, and has 
two tubular auriform appendages. (Otion Cuvieri, Leach.) 
TETRALASMIS, Cuv. 
But four symmetrical valves, which surround the aperture, 
two of them longer than the others. The animal is partly con- 
tained within the pedicle, which is large, and covered with 
hair. They are a kind of tubeless balani. (Tetral. hirsutus, 
Cuv.) 
BALANUS, Brug. 
The principal part of the shell of the balani consists of a 
testaceous tube attached to various bodies, the aperture of 
which is more or less closed by two or four valves. This tube 
is formed of various pieces which appear to be detached and 
separated, in proportion as the growth of the animal requires 
it. The gills, mouth, articulated tentacula, and anal tube, 
differ but little from those of the anatife. In 
BALANUS, 
Properly so called, the tubular portion is a truncated cone, 
formed of six projecting pieces, separated by as many de- 
pressed ones, three of which are narrower than the others. 
