CI 3.1.11 session library location and load

I'm using the latest version of CI and I have problems to load the Session Class.
First I noticed that the class-file isn't in the 'standard location' (system/libraries) but instead in session/libraries/Session.
Second even if I try to load the library in the correct way with

PHP Code:

        $this->load->library('session/session'); 


in the head of my class definition AFTER parent::__construct();

I get the following error message(s):

Unable to load the requested class: Session

I'm pretty sure to have been overlooking something as I am actually shaken by a cold too.

Any help as always very appreciated!

Greets

Guido