What do the black lemmings mean at the end of a level?

[mrpenguinb]

I'm a bit confused, sometimes the lemmings not saved (in black I assume), don't show up, and other times do.

[namida]

They show how many more lemmings you needed to reach the save requirement. For example, if the level requires you to save 5 lemmings, and you saved 3, you'll see 2 black lemmings. If you saved 5 or more, you won't see any.