Disable preview of screenshot?

When I take a screenshot on my new MacBook, a little preview icon floats on the edge of the desktop inviting me to edit it before it gets dropped onto the desktop as a file. I find this little forced pause before I can open the file in my image editor really slows down my workflow (which often involves taking several screen shots in rapid succession.

I know there's a way to forestall this little preview feature, because I fixed it on my iMac - - but I can't seem to find the control panel that governs it. Any help?

Thanks!