This is the fifth of the five terms, or bounds, into which the Egyptian table divides Leo. It runs from 24 degrees of the sign to 30, a stretch of 6 degrees held by Mars. It opens where Mercury's term closes at 24 degrees, and it closes the sign at 30 degrees, so Mars holds the last 6 degrees of Leo before the boundary into the next sign.
Set out in degree order, the five terms of Leo run Jupiter (0-6), Venus (6-11), Saturn (11-18), Mercury (18-24) and Mars (24-30). This term of 6 degrees sits between the two extremes of the sign, where the widest is Saturn's at 7 and the narrowest is Venus's at 5. The unevenness is not an accident of copying. No sign in the Egyptian table divides its five terms equally, and no two signs divide them the same way, which is why the table has to be consulted rather than derived.
The five rulers are the five planets visible to the naked eye. The sun and moon take no terms at all in this system, so each sign is shared out among Saturn, Jupiter, Mars, Venus and Mercury, every one of them holding exactly one stretch of it. A planet standing anywhere between 24 and 30 degrees of Leo is standing in Mars's bound, and Hellenistic technique reads the lord of the bound from the degree occupied rather than from the sign as a whole. The table this atlas follows is the Egyptian one, transmitted by Vettius Valens in his Anthologies and recorded by Claudius Ptolemy in the Tetrabiblos, which stayed in ordinary use after Ptolemy set out his objections to it and offered boundaries of his own.