Hab. Tierra del Fuego, the Falkland Islands, and Kerguelen's Land; very abundant at half-tide mark and below it; also in the open ocean, between lat. 45° and 55° S., reaching the 65th degree of south latitude in the meridian of New Zealand.
This, the Lessonia, and Macrocystis are the three most remarkable Algæ of the Antarctic regions, especially on account of their size; the present exceeding any sea-weed, except the Lessonia and the Ecklonia buccinalis of the Cape of Good Hope, in bulk; while the Macrocystis, to which we shall afterwards allude, is the longest vegetable production known.
The nearest affinity of D'Urvillæa was considered, in the 'London Journal of Botany' (vol. ii. p. 325), to be with Himanthalia of the Northern and Arctic seas, an opinion to which one of us was led by observing how, in habit and locality, these species represented each other in the opposite Polar oceans. Wahlenberg, Bory de St. Vincent and Greville, all regard the curious pezizæform organ of Himanthalia as the frond, and the deciduous strap-shaped laciniæ as receptacles, which view is also maintained in the 'Phycologia Britannica' (t. lxxviii.) Lyngbye (the founder of the species) and Agardh, on the other hand, pronounce the frond to be swollen at the base into a bladdery stipes, furnished with strap-shaped laciniæ, over whose surface the conceptacles are scattered as in D'Urvillæa; and in Xiphophora, a genus (as pointed out by Montague) nearly allied to the present, and which represents it in a lower latitude of the Southern Ocean. In the 'London Journal of Botany' the true analogy to the bladder of Himanthalia was sought in the trumpet-shaped stipes of Ecklonia buccinalis, but in that plant the growth of stipes and frond proceeds from the earliest stage, pari-passu, whilst the bladder of Himanthalia is fully developed before the straps appear.
We have nowhere seen a good representation of the beautiful cellular tissue of D'Urvillæa utilis, which, in its fresh state, is so regular and large as to resemble perfectly in size and structure one of the two layers of cells found in honey-comb. Most of the specimens brought to Europe are injured by pressure, which can however hardly have caused the total obliteration of structure which M. Bory's plate represents; the most accurate figure we know is given in the beautiful plate accompanying M. Decaisne's 'Essay on the fructification of Algæ'.
The spores of this and the following species are divided into four, and we cannot doubt but that this division is followed by the complete breaking up of the organ into four sporules, whose future germination resembles that described by MM. Decaisne and Thuret in Fucus serratus ('Annales des Sc. Nat.' Ser. 3. vol. iii. p. 10. t. 2). The conceptacles contain probably both antheridia and spores, so far as we can judge from drawings taken from the living plant, though at the time these bodies were not recognized as belonging to two differents classes of organs.
The northern limit of D'Urvillæa will probably be found to be the latitude of Valparaiso, or 33° S., on the West coast of South America, and 50° S., on the opposite shores of the same continent. In New Zealand it attains the parallel of 40°, but whether it inhabits any of the shores of Tasmania, or is there represented by the Fucus potatorum, is a question we cannot answer. Though carried by the currents along the ocean to the south of the Cape of Good Hope, (for it was collected in that meridian in the 51st degree, floating in the open ocean,) it does not appear to inhabit or be cast upon the southern extremity of Africa; and in the Indian Ocean, again, its range is not likely to be north of the Islets of Prince Edward's, the Crozet group and Kerguelen's Land. On the other hand, the south latitude it attains is probably regulated by the position of the Pack Ice, to within a few miles of which it was traced by the Antarctic Expedition, on one occasion, south of New Zealand to the 65th degree, which is probably its "ultima Thule" in any longitude; for it was there the last trace of vegetation. It grows invariably accompanied by the Maerocystis pyrifera.
Bory de St. Vincent states, on the excellent authority of D'Urville, that the poorer classes of West Chili use this plant for food, and that when made into soup it is very palateable, being sweet and mucilaginous. In Kerguelen's Land its enormous and weighty fronds, sometimes ten feet long, and almost too heavy for a man to lift, form the only shelter for the shells and soft animals, which there find a refuge from the flocks of aquatic birds that cover the shores and follow the receding tide.
