Shear Transfer Diaphragms are designed to attach a new shear wall and foundation to the floor above it.  A properly built foundation and shear wall can absorb a lot of force, so it is necessary to connect the shear wall to two or even three floor joists rather than just one.  I am sorry, all I have is this difficult to understand drawing, but I simply don’t have any photos.  If you can’t make head or tail from this drawing you are not alone.