406 Dansk Botanisk Arkiv, Bd. 3. Nr. 1. 



cording to the dimensions of the cells. Here and there, towards 

 the cavity in the interior of the thallus, some of the cells in the 

 membrane and diaphragms bear some smaller, irregularly stel- 

 late cells provided with shorter or longer prolongations (Figs. 

 390 A, B, C). Some of the prolongations of these cells are con- 

 nected with the adjacent cell as seen in Fig. 391. 



Upon the stellate cells one or, more rarely two nearly glo- 

 bular or short pyriform glands occur (Figs. 390 E, 391). 



I have found only tetrasporic plants. The tetrasporangia 



Fig. 391. Coelarthrum Alhertisii (Piccone) Borgs. 

 Membrane-cells from the inner side with stellate cells and glands. 



(About 275:1). 



are formed in the cortical layer and are cruciately divided ( Fig. 

 390 G). Their diameter reaches a length of about 25/^. The tetra- 

 sporic plants were gathered in the month of March. 



The cystocarps occur, according to a specimen from Guade- 

 loupe collected by Schramm, scattered over the thallus (Fig. 

 389 5); they are hemispherically prominent and provided with 

 a small apical porus. 



At the islands this plant has been dredged only once in the 

 sea to the north of St. Jan: off America Hill west of Tortola. I 

 discovered it in a collection of several living algæ which Dr. Th. 

 Mortensen, visiting the islands for zoological investigation, 

 most kindly sent to me. It was dredged in deep water (about 15 

 fathoms) in rather open sea. 



Geogr. Distrib.: Canary Islands, Guadeloupe, Bermuda. 



