Create table & serial question

Hello all
If this is too trivial... sorry. :o(((

I have created a table with the following command:

CREATE TABLE ROUTE
(
    ID SERIAL ,
    START DATE ,
    PRIMARY KEY ( ID )
) ;

And it worked just fine. But if I call:
INSERT INTO ROUTE VALUES(10, '10/10/1999') ;
it ads a record but the id is 10. Is this the correct behaviour for the
SERIAL type? I was hoping it will be 1 and ignore the one that I set.

If this is the normal behaviour, how can I make it ignore the 10 and place
the next id?

Tx
dovle