resting alga is one of his recent acquisitions, and not the leastbeautiful. As yet it must be accounted extremely rare.

Polysiphonia spinulosa belongs to the genus Hutchinsia,constituted by Agardh in honour of the late excellent MissHutchins. He could not, however, have been aware, thatMr Robert Brown had previously given the same name toa genus of the Order Cruciferce. As there is no doubt attach-ed to the propriety of Mr Brown’s genus, it is absolutely ne-cessary to change that of Agardh ; and it is only to be la-mented, that the great knowledge Miss Hutchins possessedof Marine Algae , cannot be commemorated by bestowing hername on a group of that order. The name I have now givento the genus, is derived from the peculiar structure which allthe species possess.

Fig. 1 . Polysiphonia spinulosa, nat. size. Fig. 2. A branch magnified, Fig -A portion of a main branch, with a tubercle. Fig. 4. The termination of abranchlet, with the pellnoid filaments. Fig. 5. Tubercle.