CLASS SECOND. 
CONCHIFERA. 
“" Animals soft, with articulations, destitute of a head or 
organs of vision, and always fixed within a Biva.ve shell ; 
provided with external branchiz ; a simple circulation and 
a unilocular heart. 
All the species are aquatic, living either in the sea or 
fresh water. None of the animals have an internal shell, 
the body is invariably soft, and the mouth is situated near 
the left side of the hinge. 
Lamarck divides this class into two orders, with the fel- 
lowing characters : namely, 
I. Monomyaria.— With one muscle of attachment ; 
the shell marked interiorly with one subcentral muscular 
impression. 
II. Dimyarta. — Provided with at least two muscles of 
attachment ; shell marked interiorly with two separate and 
lateral muscular impressions. 
GRAND-DIVISION I. 
Ligament none, or unknown, or in its stead a tendinous chord, which ca 
ports the shell. 
ORDER I.— MONOMYARIA. 
Animals provided with but one muscle of attachment, or 
adductor muscle, which leaves one subcentral muscular im- 
pression inside of each valve. 
TRIBE J.— BRACHIOPODA. 
Shell bivalve, adhering to extraneous marine bodies, 
either by the shell itself being in contact with them, or 
attached by a tendinous chord. Shells not quite equivalve, 
and open by a hinge. 
Genus 1.— LINGULA. — Bruguiere. 
Generic Character. — Shell equivalve, equilateral, oblong- 
ovate; compressed; thin; acute and gaping at the um- 
