You have what I believe is a brick on stone foundation. What you are noticing is years of slow decay and wear-should you be concerned-me personally I say no. I have a house built in 1875 with I believe the same style foundation. The powderized mortar in the joint actually help my house deal with moisture going in through the foundation. I actually had a hole in my basement foundation wall (a cool breeze would flow in from it) where a brick fell out. All I did was clean the area, mixed some mortar, and fit the new brick in & mortared shut. There are two layers of brick with these walls, one exterior-an air gap-and the the brick you see in your basement. Unless you see a major stress crack or an area that is excessively wet I would move on to the next project!