> Iain, I think there may be a difference between "royal" lines in Scotland > based on primogeniture and the derbhfine system in Ireland. I can see any > one "royal" line dying out - but not so much a system based on cousins. The idea of a Scottish derbhfine system is the basis of G.A. MacGregor 2006 justification of Clann Donnachaidh's origin from the Celtic Earls of Atholl. I learn from G.A. MacGregor that in medieval Scotland there was land deemed heritable only in the male line, i.e., could not be passed by marriage, but held by derbhfine. It is through the continued ownership of Glenerochie that G.A. MacGregor makes the case for Clann Donnachaidh's origin from the Celtic Earls of Atholl http://design15.clickstay.net/supplement/Mag2007.pdf