delete an inherited class

if i make a class that inherit another class, when i delete the
pointer casted to the inherited class, only the destructor of the
inherited class fires, the base class does not.

ex:

class shape
{
 ~shape()
}

class square : class shape
{
 ~square()
}

square pSquare = new square();

shape pShape = dynamic_cast<shape *>(pSquare);

delete pShape;  <== only calls  ~shape()

-- 
      [ See http://www.gotw.ca/resources/clcm.htm
for info about ]
      [ comp.lang.c++.moderated.    First time posters: Do this! ]