Google add my other links under my site on serp

What does this mean? manual review?

[iProgram]

One of my page ranks #1 for keywords "blue widget" and I noticed that four additional links on that page are listed under my site description:

blue widget
blue widget. Are you looking for a bla bla blue widget?....
www.mysite.com/blue-widget.html - 12k - Cached - Similar pages
Link 1 - Link 2 - Link 3 - Link 4
More results from www.mysite.com >>

# 2 site of serp
...

The URLs of link 1 ~ link 4 look like this:

[google.com...]

What does this mean? Never saw this type of serp before. There are more than 18 links on my blue-widget page but link 1 ~ link 4 are four most useful links. I don't think a machine can pick these links from 18 links.