The author, in laying before the Society a revised and condensed version of the various papers recently communicated by him, took occasion to make some additional remarks. Of these only one need be given here. He pointed out that another fundamental term is requisite besides those already used viz., Knots and Links. For three endless cords may be inseparably entangled with one another, or locked together, even if no one of them be knotted and no two interlinked.