Ant 128A: Fox Field Guide (7)
Ch. 4. Diagram 16; p. 98. Matrilineal, natolocal.
This is exactly the same system as #4 and #11 (copied below, for convenience), though now Fox uses two boxes (dashed to indicate descent, and, solid to indicate residence). The overlap of these boxes tells us that the matrilineal descent group, combined with natolocality for the males (the brothers), results in overlapping descent and residence groups. Fox depicts the marriage tie with a dashed line in his figure, in order to indicate that the 'husbands' are sexual companions of the females but not co-resident spouses.
Ch. 3. Diagram 17; p. 107. Matrilineal, virilocal, avunculocal.
This is another variant on the matrilineal case. There are quite a few of these (unlike the patrilineal case) because matrilineal societies have no easy way of reconciling the position of males (as fathers of their own children and as uncles to their sister's children). This is especially true when principle 3 is paramount: "The men usually exercise control," that is, when there either are significant resources or offices to inherit. Inheritance often passes from a man to his nephews and is facilitated if they are in contact.
In this instance, the women of the matriline live viri-locally with their husbands, and the men bring in wives to be co-resident with them. Children remain with their mother (non-resident with the matri-line) until they are adults, when they, especially the males, return to live with their maternal uncles, in the matriline resident group.
This diagram depicts the situation for adults, that is, after the male children have moved back to the matrilineal residence. Note that the circled sons are shown living residentially with their maternal uncles, not with their mothers, who, while they are members of the matriline, are away living with their husbands. Any younger children, and sometimes adult female children, will remain with the mother.
In Fox's diagram the arrow is meant to show how male children of the matriline move from their mother's household (where they aren't depicted) to their mother's brother's household. Thus, out of a matrilineal system and viri-local marriage comes an avunculocal residence for the adult son(s).