The accumulation of sea-weed in the neighbourhood of the African coast has been often spoken of by ancient writers. The locality of this accumulation is a problem which is intimately connected with our conjectures respecting the extent of Phœnician navigation. The Periplus, which has been ascribed to Scylax of Caryanda, and which, according to the researches of Niebuhr and Letronne, was very probably compiled in the time of Philip of Macedon, describes beyond Cerne a quantity of fucus forming a weed-covered sea--a kind of “Mar de Sargasso;” but the locality indicated appears to me to differ very much from that assigned in the work entitled “De Mirabilibus Auscultationibus,” which long bore, unduly, the great name of Aristotle. (Compare Scyl. Caryand. Peripl. in Hudson, vol. ii. p. 53, with Aristot. de Mirab. Auscult. in opp. omnia ex. rec. Bekkeri, p. 844, § 136.) The pseudo-Aristotle says, “Phœnician mariners, driven by the east wind, came in four days’ sail from Gades to a part where they found the sea covered with reeds and sea-weed (θρύον καὶ φῦκος.) The sea-weed is uncovered at ebb and covered at flood tide.” Is he not here speaking of a shallow place between the 34° and 36° of latitude? Has a shoal disappeared in consequence of volcanic eruption? Vobonne speaks of rocks north of Madeira. (Compare also Edrisi, Geog. Nub., 1619, p. 157.) In Scylax it is said, “The sea beyond Cerne is unnavigable on account of its great shallowness, its muddiness, and the great quantity of sea grasses. The sea grass lies a span thick, and is full of points at the top, so that it pricks.” The sea-weed found between Cerne,--(the Phœnician station for laden vessels, Gaulea, or, according to Gosselin, the small island of Fedallah, on the north-western coast of Mauritania),--and Cape de Verde, does not now by any means form a great sea meadow, or connected tract of fucus, a “mare herbidum,” such as exists beyond the Azores. In the poetic description of the coast by Festus Avienus, (Ora Maritima, v. 109, 122, 388, and 408), in the composition of which, as Avienus himself says, (v. 412) he availed himself of the journals of Phœnician ships, the obstacle presented by the sea-weed is referred to in a very circumstantial manner; but its site is placed much farther north, towards Ierne, the “Sacred Island.” Sic nulla late flabra propellunt ratem, Sic segnis humor æquoris pigri stupet. Adjicit et illud, plurimum inter gurgites Exstare fucum, et sæpe virgulti vice Retinere puppim.... Hæc inter undas multa cæspitem jacet, Eamque late gens Hibernorum colit.