lately been erected into a distinct genus, by Kiitzing, under the name of Plerocaulon, and on grounds equally valid with those which separate some of the above groups. Seirococcus was distinguished from Scytothalia by Dr. Greville, by having moniliform instead of oblong or lanceolate receptacles; but the genera have been reunited by Montague, who has added a new species (Scyt. Jacquinotii) , and this last approximates so closely to Marginaria, as to reduce the clearly appreciable differences between Scytothalia, Mont., and Marginaria, to the former having entire and the latter spinuloso-dentate margins, — a circumstance of very minor importance, and perhaps of specific value only. Carpopliyllum, may be distinguished by the position of its vesicles and the clustering of its receptacles from Fucus ; on the other hand it approaches Sargamim through S. Boryi, Ag. Marginaria contains but two species, of which Kiitzing in his late work constitutes as many genera. A. Richard, on the contrary, struck with the slight characters on which he had established Marginaria, afterwards combined it with Sargassum.
The paraphyses, so carefully described by Montagne in the generic character as occuring mixed with the spores, answer well to the antheridia observed lately by MM. Decaisne and Thuret in Fucus, whence this species would be regarded by these authors as hermaphrodite.
1. Mahginapia Urvilleana, A. Rich.; Montagne Prodr. P/tycear. in itin. ad Polum Antarct. p. 10. Voy. an Pole Sud, Pot. Crypt, p. 60. t. 3. f. 1. A. Rich. Fl. Nov. Zel. p. 10. t. 3. Sargassum Urvilleanum, A. Rich. Serf. Astrolab. p. 138. A. Cunn. in Hook. Comp. to Pot. Mag. vol. ii. p. 327.
Hab. Lord Auckland's group ; very abundant in shallow water. Pinna 12-18 unc. longee, £-1 unc. lata?, coriaceo-membranacese, nigro-fusca3j plana?, laeves, enerves, argute serratae, obtusae, basi sensim attenuates, subpetiolatas, irregulariter dichotome fissae, ramis superioribus plerumque simplicibus, inferioribus divisis, sinubus angustis rotundatis, laciniis erecto-patentibus. Vesicula sphaericae, 4-8 lin. latae, muticse, petiolo inconspicuo piano 1 lin. longo suffultae, margine pinnulamm superiori affixae. Receptacula breviter peduncidata, 2-3 lin. longa, ad basin frondis secus marginem superiorem in serie elongata inserta, divaricata, lanceolata, obtusa, compressa, torulosa. Conceptacula globosa, receptaculis immersa, demum plus minusve convexa, poro pertusa. Spora exemplaribus nostris immaturaa.
Dr. Montagne enumerates Blossevillea retorta, Mont., and B. retrofiexa, Kiitz., as natives of Lord Auckland's sjroup, and also the Carpopliyllum macrophyllum, Mont.
2. D'URYLLLEA, Pory.
1. D'Urvillea utilis, Bory in Duperrey Voy. Pot. Crypt, p. 65. 1. 1 and 2. f. 2. If Urville, Fl. Ins. Mai. in Mem. Soc. Linn. Paris, vol. iv. p. 594. Montagne, Crypt. Poliv. et in Voy. au Pole Sud, Pot. Crypt. p. 23. Decaisne in Arcldv. 3Ius. vol. iv. p. 153. t. 5. f. 1-6. Postels et Rnppr., Illust. Alg. t. 1. Fucus antarcticus, Ckamisso in Choris, Toy. Pittor. t. 7.
Hab. Lord Auckland's group and Campbell's Island, and in the open sea for ten degrees southward of these groups.
The distribution of this species will be considered with that of the genus Macrocystis in the second portion of the Flora Antarctica.
3. XIPHOPHORA, Mont.
Frons olivacea, linearis, compresso-plana, coriacea, dichotome ramosa. Vesicida nullae. Conceptacula per totam frondem sparsa, ramis immersa, tuberculiformia, poro pertusa, intus naturae diversae ; altera sporas obovatas, nigro-fuscas, demum quadripartitas, limbo hyalino cinctas, parietibus affixas, sessiles ; altera fasciculos filorum ramosorum, articulatorum, apicibus turgidis et demum in corpuscula granulis repleta (antheridia vel gemmas) mutatos foventia.
We fullv agree with our excellent friend Montagne in the propriety of establishing the present genus, and
