The shortest thing I can think of that will do well in full shade and will like your wet conditions is Ajuga. If the cracks are small, one of the smaller leaf varieties like 'Chocolate Chip' would probably work well. But slugs will definitely enjoy dining on it, so I'd recommend you get out the slug bait now to start trying to control them before you even start to plant. Spread it under the leaves of the plants you already have---if you have hosta, I'm surprised you have any leaves left on them! Hosta is slug candy! You'll need to replace it every couple weeks (or more often if you really have a lot) and after it rains.

? moss?
Mazus reptans- it's listed as sun/partshade, but I know some folks use it in shade around here.

The dirt areas are rather large as I have the stepping stones spaced about a normal pace apart. The ferns and hostas are to the sides since my dog uses this area to access the large fenced back yard. The slugs have never seemed to bother the hostas at all but they sure do climb on the fountain I have in there! And these are those darn big slugs that stretch to about 5-6 inches and as big around as my little finger. I'm not much of a gardener so will have to look up the varieties you both mentioned. I had wondered about moss and read the "recipes" for spreading yogurt and/or buttermilk and coating with a blended mixture of moss. Only problem is getting to the woods to find the moss to start with. LOL. Thanks much to both of you.

If you decide to use Ajuga, I'd recommend a larger one than 'Chocolate Chip' since you have larger areas to cover. 'Bronze Beauty' is a variety that should be very easy to find and it's also very easy to grow and will spread pretty quickly. Here's a link to basic info about it on perennials.com. If you're looking at other Ajuga's, I recommend staying away from 'Burgundy Glow'. It's real pretty, but it can often be quite a bit more difficult to grow than most of the other varieties.

Mazus reptans could be a real pretty cover for you too, but if you really don't have any direct sun at all, I think it might get too leggy to look good. For basic info on it, just type Mazus into the #2 search box on perennials.com. Why don't you try a few different things to see how they're working out for you--put the mazus in the brightest spot.

With the slugs, I guess if they're not eating your plants (and you don't mind slime?) there's no problem with just letting them be! But, I checked your bio, and since you're a "wildlife" lover, why don't you collect them some morning or evening and relocate them to a nearby woods where (if they're banana slugs) they can happily help compost the fallen debris.

Whoops! Guess I had a senior moment! Here's the Ajuga link.

Here is a link that might be useful: 'Bronze Beauty' Ajuga

Thanks for all the info Skybird. Yes I do have a "thing" about all critters. Heck I even try to get house spiders in a jar so I can relocate them outside! I don't know if moving the slugs would do much good. Something about this yard really attracts them. This is the old home place that grandparents bought in 1949 and we've always had slugs so that could be a never ending job. LOL. I don't know what variety they are - dark grey with some black specks and LONG! Only time I get upset with their slime is when my dog wants to lay outside a while of an evening and comes in with that gunk and an assortment of leaves, twigs and whatever stuck to her side!

I am using a combination of Fragaria virginensis, Tiarella cordifolia and Viola labradorica between stepping stones. Symphytum grandiflorum is reasonably well-behaved in total shade, but is rampant given some sun. In a sunnier area between stepping stones I am using Chrysognum virginianum

Though I usually don't recommend it because it can get rampant in a "controlled" landscape, Lamiastrum (Yellow Archangel) would look pretty vining here and there. And if you have a little sunnier area the Chrysognum virginianum (Green & Gold) is a native here and a yellow blooming treasure all summer that needs at least reflected sun.

I've used Creeping Jenny in a similar situation. It really likes moist areas. Check it out.

I wonder if Asarum europeum might not work nicely for you, too.

I absolutely love it! and it is very happy in my shaded garden, reseeding beautifully. I have slugs here, too, and I've not noticed that they inflict any damage on Asarum. This plant doesn't spread quickly... you will have to be patient, but if it takes a shine to the area it will steadily colonize forming a lovely mat of kidney shaped leaves that are glossy and often persist through the winter.

Vinca minor might also be an option for you. I love "Myrtle", but it can get out of hand and while I'm not sure of this, I believe it has been listed as invasive in some states. So be careful and do some research before you sign on willy-nilly.

thegardenhelper.com has a section of ground covers for full shade. Check it
out.

Nothin beats moss in shady and wet, Check out this link

Here is a link that might be useful: Moss Yard