23 



the base of old sporangiophores in several species, and in the rhizome-filaments of A. nigricans. 

 The distribution of A. Rawsoni is confined to the West Indian region. 



.-• 



2. Avrainvillea nigricans Decaisne 



s ' 



in Ann. Sci. Nat. 2«ie s é r . V ol. iS. 1842 p. 108. 

 Syn. Fradelia fuliginosa Chauvin, Recherches — , Caen 1842. p. 124. 



Avrainvillea sordida var. longipes Crouan ex Mazé et Schramm Algues de la Guadeloupe. 



2me édition. 1870 — Jj. p. 90 (pro parte). 

 Rhipilia longicaulis Dickie in Journ. Linn. Soc. (Bot.) XIV. 1874. p. 312. 

 Avrainvillea nigricans J. G. Agardh Till Alg. Syst. V. 1887. p. 53. 



Avrainvillea nigricans Murray & Boodle in Journ. of Bot. XXVII. 1889. p. 70 (pro parte). 

 Avrainvillea longicaulis Murray & Boodle in op. cit. p. 70 (pro parte), tab. 228, figs. 1 — 5. 

 Avrainvillea nigricans Murray in Journ. of Bot. XXVII. 18S9. p. 238 (pro parte). 

 Avrainvillea longicaulis Murray in Journ. of Bot. XXVII. 1889. p. 238 (pro parte). 

 Avrainvillea nigricans De Toni Syll. Alg. I. 1S89. p. 513 (pro parte). 

 Avrainvillea longicaulis De Toni Syll. Alg. I. 1889. p. 514 (pro parte). 

 Avrainvillea nigricans Hovve in Buil. Torrey Bot. Club XXXIV. 1907. p. 509. 

 Avrainvillea nigricans Börgesen in Vid. Medd. nat. Foren. Kjöbnhavn 1908. p. 30. 

 Avrainvillea nigricans Vickers & Shavv Phycologia Barbadensis. Paris 1908. p. 23, pi. XXX. 

 Avrainvillea longicaulis Vickers & Shaw op. cit. p. 23, pi. XXXI. 

 Avrainvillea nigricans Collins Green Alg. N. Amer. in Tufts College Studies II. 1909. p. 390. 



Hab. ATLANTIC. Guadeloupe, Hes des Saintes, d' Avrainville ! — Point a Pitre, Het a Jarry, Mazé 

 n" 174 bis in Herb. Mus. Brit! also n° 174 and 174 bis in Herb. Kew ! — Saintes, anses 

 du vent, sur la coquille d'un Strombus, Mazé n° 11 26 (sub nom. " Avrainvillea sordida var. 

 longipes") — Florida, Caesar's Creek, in mangrove mud, near low-water mark, M. A. Hozve 

 n" 29(53 in Herb. Kew ! — Bahamas, Cave Cays, Exuma Chain, M. A. Howe n u 3982, in 

 Herb. Kew! and Great Guana Cay, Exuma Chain, M. A. Howe n° 4052, in Herb. Kew! 

 and New Providence, M. A. Howe n° 3335, in Herb. Kew! — St. Thomas, "Challenger" 

 Expedition, 5 — 15 fathoms in Herb. Mus. Brit! and Kew! — Antilies, Herb. Shuttleworth\ — 

 Jamaica, Montego Bay, Pease & Butler, Phyc. Bot. Amer. n° 770, in Herb. Mus. Brit! — 

 Barbados, Bath, Vickers n" 40 (sub nom. A. longicaulis)] — Brazil, Pernambuco, Fr adel} — 

 Bermuda, " Challenger" Expedition, sub nom. Rhipilia longicaulis, Dickie in Herb. Kew! 



"Usually fusco-nigrescent when living or rarely tawny-green, of a similiar colour on 

 "drying or somewhat darker or more sordid, gregarious or scattered, normally with a stout 

 "horizontal rhizome (commonly left in substratum as ordinarily collected), or, when small and 

 "poorly developed, with a somewhat bulbous or difform base: stipe cylindrical or flattened, 

 "1 — 16 cm. long, 3 — 14111111. wide, now and then deficiënt or scarcely differentiated, simple or 

 "rarely forked near the base: flabellum varying from suborbicular (reniform-cordate when young) 

 "to cuneiform (sometimes subclavate when young), 1 — 25 cm. broad, entire or more or less 

 "lacerately or digitately lobed, thin and membranous in the broader forms, thicker and more 

 "coriaceous in the narrower, felt-like in texture, very obscurely or not at all zonate, the surface 

 "subvelutinous or minutely spongiose: filaments of flabellum distinctly moniliform or torulose 

 "(at least those near the surface) usually firm-walled and rather straight and rigid, 33 — 70 u. 

 "in maximum diameter, filaments of stipe similar, but with more differentiation between those 

 "of surface and those of interior: sporangia mostly subpyriform, varying from clavate to 

 "subglobose, 0.35 — 0.83 mm. Xo.20 — 0.35 mm., usually exserted once or twice their own length ; 



