193 



The basal cells are oblong rectangular and arranged in fairly 

 clear rows, occasionally dicliotomously divided (Fig. 149 b). 



From these cells the assimilating filaments grow up. These 

 are likewise now and then dichotomously divided and composed 

 of rather short cells; the diameter of the filaments, which are 

 rather firmly connected, is about 8 — 10 ju. 



The chromatophores were not very clear, even after having 

 been stained ; nevertheless I think that each cell contains a few 

 irregular discs. 



Fig. 149. Lithoderma spec, 

 a, transverse section of thallus. b, part of tlie disc. (About 200: 1). 



As the plant was sterile any more precise determination 

 w^as excluded. 



Only found once upon a stone in quite shallow water. 



St. Jan: Cruz Bay. 



Fam. 7. Cutleriacece. 



Aglaozonia Zanard. 



1. Aglaozonia canariensis Sauv. 



C. Sauvageau, Observations sur quelques Dictyotacees et sur un 

 Aglaozonia nouveau (Bulletin de la Station biologique d'Arcachon, 8, 1904—5). 



BoRGESEN, F., Two crustaceous brown alga3 from the Danish West 

 Indies (Nuova Notarisia, Serie XXIII, 1912). 



On the exposed coast of the rocky north-west side of St. 

 Croix I have collected a crust-shaped alga which seems quite to 



