Well I, and many others, thought that this was missing, since there's no longer an arrow to click on in the search field, make that the "omnibar." But it turns out that there's an easy way to get to your search history. Just click in the omnibar, or press Command-L, and press the spacebar. The Recent Searches menu will display, along with the options to change search engines.
Thanks to marmalito who posted a comment to this Macworld hint post.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20120807003912570