storage engine , mysql syntax CREATE TABLE t (i INT) ENGINE = INNODB|BDB

In mysql, we can wrote a create table like 
CREATE TABLE t (i INT) ENGINE = INNODB||BDB|;
where the storage engine is the innodb one. 
This allow to have differents kind of storage format, and allow to easly implements memory table or remote table. 
I try to make the same thing for postgresql but i do not understand where the logical storage engine is in the source
code.
May i have somme help to find it .
Thank you.
pierre