ELEMENTS 
OF 
CONCHOLOG Y. 
INTR(3DUCTION. 
CoNCHOLOGY or Tcstaceology is the science which 
treats of the structure, appearance, properties, and 
methodical arrangement of Shells, the external 
testaceous covering of certain molluscous animals, 
Testacea constitute the Illd Order of Vermes, 
the Vlth Class of the Linnsean System of Nature. 
This order includes all shells of a calcareous na- 
ture, that is, composed of carbonate of lime mixed 
with some gelatinous matter; and excludes those 
which are called crustaceous, in the covering of 
which phosphate of lime is a constituent part, 
B 
