I do not see the scrolling option of vertical only at the bottom of the page.
I am running Mac OS X 10.7.5. Do I need to upgrade to the new OS X Mountain Lion to see this option?
With OS X 10.7.5 I see:
Options available on "Point & Click tab are: 1. scroll direction: natural, 2. secondary click, or 3. smart zoon
Options available on More Gestures tab are: 1. swipe between pages (using one finger); 2. swipe between full-screen apps (with two fingers), or 3. Mission Control (double tap with two fingers)
Try this. Not sure it works in 10.7, but it won't hurt anything if it doesn't. Only problem is this doesn't appear to last through a restart.
Open Terminal (in your Applications/Utilities folder):
Copy/paste and hit Return:
defaults write com.apple.driver.AppleBluetoothMultitouch.mouse MouseHorizontalScroll -bool NO
Turn your mouse off and then on again from the power switch
defaults write com.apple.driver.AppleBluetoothMultitouch.mouse MouseHorizontalScroll -bool YES