LECTURE XL 
TThE Linngean Mollusca Testacea^ or Soft-bo- 
died Animals furnished with Shells , are divided into 
three assortments, called Univalves, Bivalves, and 
Multivalves ; meaning, that the shelly cover con- 
sists either of one, two, or several parts or valves, 
A Univalve Shell may be exemplified by that 
of the common snail ; for the shell is simple or un- 
divided. A Bivalve Shell may be exemplified by a 
Muscle, in which, as every one knows, the shell is 
composed of two pieces or valves j and lastly a 
Muliivalve Shell may be exemplified by any spe- 
cies of Lepas or Bernacle, in which the shelly co- 
vering of the animal is formed of several pieces or \ 
divisions. 
The animals inhabiting by far the greater part 
of the Univalve shells are formed on the plan of 
the common Garden Snail, to which they bear a 
great general resemblance, though furnished, in 
