(a) Subject to subsection (b) of this section, and to section 19-319, when the intestate leaves a child and a child of a deceased child, the child of the deceased child takes such share as his deceased parent would, if living, be entitled to, and every other descendant in existence at the death of the intestate stands in the place of his deceased ancestor.
(b) Those in equal degree claiming in the place of an ancestor take equal shares.