. MARINE ALGAL VEGETATION 



149 



luxuriant on this species than on the remaining Laminariacece. It 

 happens rather frequently, however, that a rich epiphytic vegetation 

 occurs on L. diyitata, L. saccharina, Alaria esculenta and Saccorrhiza 

 dermatodea. The epiphytes generally occur most abundantly on the 

 older individuals. The vegetation on the stems is usually composed 

 of species which may be found growing among the Laminarice, 

 and then belong to the second layer of the under-vegetation, which 

 can thus be raised upon the Laminaria stems; consequently, it is 

 very natural that the composition of the species of the epiphytic 

 vegetation should vary according to the depth. The following 

 distinction is evident: that the semi-littoral species which grow 

 epiphytically in shallow water vanish as the depth increases; while, 

 on the other hand, some of the deep-water species may occur at a 

 relatively lesser depth. 



The following species have been found to occur on stems of 

 Laminariacece, and may almost all be found on Laminaria hyper- 

 borea: 



Ahnfcltia plicata. 



Antithamnion floccosum. 



A. Plumula v. boreale. 



Ceramium rubrum. 



Delesseria alata. 



D. sanguinea. 



D. sinuosa. 



Dermatolithon macrocarpum. 



Euthora cristata. 



Gigartina mamillosa. 



Lithophyllum Crouani. 



Lithothamnion circumscriptum. 



Lomentaria clavellosa. 



L. rosea. 



Odonthalia dentata. 



Petrocelis Hennedyi. 



Peyssonellia Rosenvingii. 



Plocamium coccineum. 



Polysiphonia arctica. 



P. parasitica. 



P. urceolata. 



Porphyra miniata. 



Ptilota pectinata. 



P. plumosa. 



Rhodochorton repens. 



R. Rothii. 



Rhododermis parasitica. 

 Rhodophyllis dichotoma. 

 Rhodymenia palmata. 

 Desmarestia aculeata. 

 D viridis. 



Ectocarpus confervoides. 

 E. fasciculatus. 

 E. Hinksiae. 

 E. penicilliformis. 

 E. siliculosus. 

 E. tomentosoides. 

 Isthmoplea sphserophora. 

 Laminaria digitata. 

 L. hyperborea. 

 Leptonema fasciculatum. 

 Litosiphon filiformis. 

 Sphacelaria olivacea. 

 S. radicans. 

 Monostroma fuscum. 

 M. Grevillei. 

 M. undulatum. 

 Ulothrix flacca. 

 Ulva Lactuca. 

 Ulvella fucicola. 

 Urospora Wormskioldii. 



51 species in all. 



In addition, the fungus Dothidella Laminarice must be men- 

 tioned; it is a very common endophyte in the stipe of various 



