rationalibus divisis

from Bouvier's Law Dictionary, Revised 6th Ed (1856)
RATIONALIBUS DIVISIS, WRIT DE. The name of a writ which lies properly when 
two men have lands in several towns or hamlets, so that the one is seised of 
the land in one town or hamlet, and the other, of the other town or hamlet 
by himself; and they do not know the bounds of the town or hamlet, nor of 
their respective lands. This writ lies by one, against the other, and the 
object of it is to fix the boundaries. F. N. B. 300. 
    

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