58 Dansk Botanisk Arkiv, Bd. 2. Nr. 2. 



Besides D. Brongniartii J. Ag. Hauck refers some other species 

 to this plant e. g. also D. Mertensii Kiitz. Most probably Hauck 

 is right in referring the latter to this species; in my collection I 

 have not found any form which I feel can be referred to it. 



Dictyota denlata occurs in shallow water in sheltered places 

 and in deeper water (about 10 meter) in more open sea. 



It has been found: St. Croix: At the entrance to Christiansted's 

 Lagoon, Saltriver, Casavagarden, Green Key and near Buck Island. 

 Geogr. Distrib. West Indies, Brazil. 



Dilophus J. Ag. 



1. Dilophus alternans J. Ag. 



J. Agardh, Till Algernes Systematik, V, Dictyoteæ, p. 108; Analecta 

 algologica, Continuatio I, 1894, p. 93. A. Vickers, Phycologia Barba- 

 densis, pi. X. 



The specimens found agrees well with the figure of M lle 

 Vickers (1. c). All were sterile. 



This species has been found in the upper sublittoral region 

 and in somewhat sheltered places. 



It was collected, St. Croix: Lime Tree Bay; St. Jan: Coral Bay. 

 Geogr. Distrib. West Indies and surrounding coast. 



2. Dilophus guineensis (Kiitz.) J. Ag. 



J. Agardh. Till Algernes Systematik, 2dra Afd., p. 108. J. Agardh, 

 Analecta algologica. Cont. I, p. 89. A. Vickers, Phycologia Barbadensis, 

 Part II, pi. IX. 



Spaloglossum guineense Kiitz., Phycologia generalis, p. 339; Species 

 Algarum, p. 560; Tabulæ Phycologicæ, vol. IX, pi. 46, fig. I. 



In the upper part of the thallus the flat frond consists of a 

 single layer of large cells surrounded by a layer of small epider- 

 mical cells (Fig. 39 a). Lower down in the thallus we find in 

 transverse section the large cells to be divided mostly into two 

 layers of cells (Fig. 39 b) sometimes in the middle of the frond 

 even into several layers. 



The base of the plant consists of terete, rhizome-like fila- 

 ments composed of several cells with thick walls. These filaments 

 are creeping and from their lower side numerous rhizoids grow 

 out ending with small attachment discs fixed to the substratum. 



