FRESHWATER AIO.K PROM JUAN FERNANDEZ VND EASTER ISLAND 91 



The specimens, however, very much resemble his figures of Diplonema 

 rupicolunt, and the false branches are exactly like those. The dimensions, 

 moreover, are quite the same as recorded by him, and I have observed the 

 curious chroococcoid stage which occurred interiorly in the frond. 



To judge from his drawings the species presents a considerable range of 

 variation and certainly the Myxophycea observed comes nearer to Diplonema 

 rupicolunt than to any other species. 



Masatierra: on rocks in cave. 



Area of distribution: previously only known from Italy. 



Family Nostocacetc. 



Genus Nostoc Vaucher. 



18. Nostoc spheericum Vaucher. 

 Vaucher: Hist. Conferves d'eau douce. 



The determination is not perfectly sure as neither heterocysts nor spores 

 could be found. However, the macroscopical appearence and the characters 

 of the vegetative cells are facts so strongly supporting the determination that 

 there can be very little doubt concerning the identification of the specimens. 



Masatierra. 



Area of distribution : world-wide. 



19. Nostoc ellipsosporum (Desmaz.) Rabh. 



Rabenhorst: Flora Europ. Alg. ; Hormosiphon ellipsosporus Desmazieres: PI. 

 crypt, de France; Wittrock & Nordstedt: Exsicc. 1329. 



Masafuera: The typical form of this species was observed in a single 

 sample, collected on damp soil between Hepaticae. 



Size: Long. cell. 7 — 12 \x; lat. cell. 4 u.; lat. heterocyst. 6—j u.; long, 

 heterocyst. 7—13 u. ; long. spor. 12 — 19 {^1 ^ at - spor. 6—8 \).. 



Area of distribution: probably ubiquitous. 



Family Oscillatoriaceae. 



Genus Lyngbya Ag. 



20. Lyngbya sp. 



Masatierra: among other Algae. The species was undeterminable as only 

 a couple of filaments were observed. 



Distribution of the genus: world-wide. 



