Sentence:  ...the fact of the <WSD>immemorial</WSD> taking of the toll, though it would be rightful in its origin if the spot was in a port, and wrongful if it was not in a port, did not of itself afford sufficient ground for inferring that the spot was an antient port, or that such special services were rendered, either by express stipulation in some lost grant, or by <WSD>immemorial</WSD> usage, as would support such a grant or custom. 
Meaning of the word marked with <WSD> tags:  Ancient beyond memory.