Google may be testing allowing mobile searches using image search to jump from page to page of the search results instead of the infinite scroll. Bhumika Kateliya posted this screen shot on Twitter of Google Images results on mobile having a page 2 button behind a blue background.
Here is the screen shot:
It is weird because it shows the images below page two, when it is really just scrolling down.
Bhumika wrote "Image results showing "Page 2" but didn't explain much more. It seems like Google is still using infinite scroll but it documenting what is on page two versus page one and other results.
Forum discussion at Twitter.