1. The initial row of Splachnidium is similar in origin and development to the "initial" of the Fucaceae, except that in Splachnidium it involves an entire linear row of thallus tissue; it may or may not include a terminal hair; and it accompanies vegetative as well as reproductive activity. 2. It seems unwise to place Splachnidium under a separate family; rather is it preferable to retain it under the Fucaceae, regarding it as a primitive member of that group for the following reasons: (a) it closely resembles the Fucaceae in the structure of the thallus, but has an apical meristem in place of a segmenting apical cell with consequent dichotomy; (b) true conceptacles are present which in origin and development are of the same general type as those of the Fucaceae, but are scattered indefinitely over the entire plant body; (c) the reproductive sacs may prove to contain isogamous gametes.