Note to King Lear, 1.1.128

King Lear,
Act 1, Scene 1, line 128
With my two daughters' dowers digest this third: i.e., in addition to the lands I granted to Goneril and Regan as their dowries, divide between you the other third of the kingdom intended for Cordelia. —The word "this" may indicate that Lear is pointing to his map of the division of the kingdom.

Cordelia's Portion by Ford Maddox Brown (1821 - 1893)
Source: Now My Charms Are All O'erthrown