MARINI. AI.r.AL COMMINITIES OF THK JLAN FERNANDEZ ISLANDS 68 I 



be distinguished, one forming a continuous cover on rock and the other en- 

 crusting loose stones and shells and giving rise to calcareous sand. 



With regard to the Formation of deep water Rhodophjxeae it is evident 

 tliat in Juan Fernandez waters Dictyotaccac are mucii more conspicuous than on 

 the coast of Chile, but from the Pcru\ ian c(jast several species are known. The 

 presence of characteristic green algae such as Codiutn and Microdictyoii makes 

 the Juan Fernandez, sublittoral formation e\en more mixed in appearance. 



Remarks on the geographical distribution and affinities of the 



Marine Flora. 



The CymwpJiyceae and Loralti}iaccac have not been included; of the 

 former, only 2 species were collected separately. The dift'erence between Masa- 

 tierra and Masafuera is, at least in part, due to deficient knowledge of Masa- 

 fuera. Species of wide distribution, which are known from the west coast of 

 South America, are marked also in the Peru-Chile column, etc. — Nomenclature 

 and sequence of species are as in Dr. Levrixg's paper. 



To the Subcosmopolitan group are referred widely distributed forms, mainly 

 in Temperate regions, or at least not more or less confined to warmer seas. 



The list contains 93 species. To these should be added 2 species identified 

 as to genus, and a few which could not be classified; further 2 species of Coral- 

 liua, Lithop]iylhti)i fernandeziaJuiDi and L. (Melobesia.-) sp., and one or several 

 other species of crustaceous Corallines, bringing the total number to a little 

 over 100 species. 



In a preliininar\- note on the marine flora (Xordiska Xaturforskarmotet in 

 Helsingfors, 1936) I pointed out the profound difference existing between the 

 islands and the continent, so striking even to the casual observer, who will at 

 once note the absence of the large brown algae, Durvillea, LessoJiJa, and Macro- 

 cystis, of which the latter two run along the coast as far as Peru, Macrocystis 

 reappearing on the coast of California. I remarked that the general likeness is 

 perhaps greater with the flora of Peru (and northern Chile) than with the coast 

 flora farther south, as the Subtropical element represented in the Peruvian flora 

 is even stronger in Juan Fernandez, and that the insular endemism is remarkably 

 high; further, that there is a small Australian — Xeozeelandic element which does 

 not belong to the circumpolar group of species known also from southern Chile 

 and Magellania. Finally, that a couple of Subantarctic species, also found in 

 Fuegia, the Falklands, etc., reach Juan Fernandez. ^ly conclusion was that, 

 taking into account the fact that the Humboldt current does not reach the is- 

 lands, they are surrcnmded by warmer water, but that historical causes are partly 

 responsible for the composition of the insular flora. 



Of the 93 species in Table III, 56 are confined to Masatierra, and only 8 

 to Masafuera; 29 were collected in both islands. Even if some dift'erence exists 

 between them, future investigations will very likely show that many species 

 known at present only from ]\Iasatierra, occur also at Masafuera. Xo littoral 



45 — 41438- The Xat. Hist, of Juan Fernandez and Easter Isl. Vol. II. 



