672 C. SKOT'ISBERG 



becomes confined to a very narrow belt. The storm belt is indeed wide enough, 

 but too boisterous for most non-crustaceous algae. A Diirvillea would perhaps 

 find suitable stations, but this as well as the other large Phaeophyceae, so con- 

 spicuous along the rocky shores of south Chile, are absent. Another factor 

 which helps to explain the poverty of the littoral flora is the nature of the rock. 

 In the basal region of Alasatierra it is to a great extent too easily disintegrated 

 to resist the force of the breakers, and well developed commimities were observed 

 only where hard rock was exposed. Here crustaceous Corallines will form a 

 cover even in the stongest surf, and small fruticulose species become abundant. 

 Masafuera is still more exposed than Masatierra and the litt(jral flora remarkably 

 poor as far as my experience goes. 



The upper sublittoral region is, as a rule, inaccessible either from land or 

 sea, and dredging offers considerable difficulties because of the steepness of the 

 submarine shelf. Generally it is not possible to work in water less than 25 or 30 m 

 deep without getting too close to the dangerous beach. The best results were 

 obtained in the shallow strait between Masatierra and Santa Clara. Almost all 

 my dredgings were made in water 20 m deep or more. Our knowledge of the 

 region between low-water mark and 10 m is very scanty. Whether any con- 

 siderable number of species which do not belong to the lower littoral nor descend 

 to the depths where my dredgings were made, are at home in the intermediate 

 region, is impossible to tell, but hard!}- probable. Anyhow, we have every 

 reason to believe that future investigations will reveal the existence of man}' 

 algae which have escaped notice. 



Xo tidal observations have been made in these islands. We found the 

 greatest difference between high and low tide to be ab(nit 4 ft. (= 1.2 m). 



The terminology is the same as used in my paper on Subantarctic algal 

 communities (K. Svenska Vetenskapsakademiens Handlingar, ser. 3, vol. 19, 1941). 

 Leading species, as observed directly in the littoral region, or occurring in 

 abundance in a catch from the sublittoral, are in fat types. Microscopic en- 

 dophytes are not included. 



The 1 i 1 1 f ) r a 1 region. 



St. 1. South coast of Masatierra, foot of Cerro Negro. 7.1. 1917. Beach 

 terrace of hard basalt, gently sloping inward. 



a. Deeper pools, fed by the surf through channels also in calm weather. 

 Enterouiorpha-Polysiphoiiia Ass. 



1. Upper fringe. Enteromorpha intestinalis, I'lva rigida. 



2. Lower fringe, ilva reticulata. — C7ia>it)aiis/a catnndata [on (ira), Poly- 

 siphonia abscissa. 



b. Very shallow pools with te[)id water, not washed. Calothrix vivipara 

 Ass.' 



c. Upper sublittoral. Inaccessible. Cover of crustaceous Corallines. 



' Dr. Jobs. Boye Pf.iersf.x, Copenhagen, Iiad the kindness to determine the Cya- 

 iiopliyccae. 



