85 



It can be suLorbicular or reniform often with cordate or 

 cuneate base, the margin is entire or more or less lacerated, or 

 even lobed. Most often it is not at all zonate, but specimens 

 occur which are very clearly zonate. 



On account of its very loose and felt-like texture Ai^r. nigri- 

 cans is easily recognized by the numerous small openings in the 

 flabellum through which the light passes when the specimens are 

 held up against it. 



The chromatophores in the young well-preserved fdaments 

 are small spindle-shaped plates and contain one or sometimes 

 two pyrenoids (Fig. 69 c). Much amylum is often present espe- 

 cially in the older filaments. In these the chromatophores are 

 often more roundish. It may be to these that Mr. & Mrs. Gepp 

 allude (1. c. p. 26) when they have only found round chromato- 

 phores. 



A(^r. nigricans is the most common species of the Avrain- 

 villeas in the Danish West Indies, where it occurs in deeper water 

 at a depth of about 20 — 30 meters. 



It has been found at St. Thomas: in the sea west of Water Is- 

 land; St. Jan: in the Sound between St. Thomas and St. Jan at many 

 places and near the Gr. St. James Island. 



Geogr. Distrib. Florida, West Indies, Brazil. 



2. Avrainvillea Mazei Murray & Boodle. 



Murray & Boodle, A systematic and structural account of the genus 

 Avrainvillea Decsne (Journ. of Botany, vol. 27, 1889, p. 70—1, tab. 288, 

 fig. 6). BoRGESEN, The species of Avrainvilleas hitherto found on the shores 

 of the Danish West Indies. (Vidensk. Medd. fra den naturh. Foren. 1908, 

 p. 32). A. & E. S. Gepp, The Codiaceae of the Siboga Expedition, Mono- 

 graphie LXII, 1911, p. 27, figs. 81—83. 



Avrainvillea longicaulis Howe, Phycological Studies III. (Bull, of the 

 Torrey Bot. Club, vol. 34, 1907, p. 509). Collins, The green Algae of North 

 America (Tufts College Studies, vol. II, 1909, p. 391). 



In my paper quoted I have given my reasons why I think 

 we may call this species Ai^r. Mazei and not longicaulis as Howe 

 has done and Mr. & Mrs. Gepp agree with me in their mono- 

 graph, giving there a very detailed survey of the intricate sy- 

 nonymy. 



At the shores of the Danish Isles I have only found a single 

 small, but quite typical specimen of this species. The stipe is 

 about 3 cm. long, the breadth of the flabellum 7 cm ; the whole 

 length of the plant is 7 ^ cm. The form and size of the filaments 

 agree very well with the figure of Mr. & Mrs. Gepp ; they are about 



