72 



1. Erythroeladia irregularis sp. nov. 



Tliallus minuius, ambitu inegulari. Fila laleialiler lamosa, iiiegulariler ra- 

 diantia, stepe maxima pro parte inter se discreta. Rami plerumque in cellula sub- 

 terminali nascuutur. Cellulse plerumque oblongse, long. 7 — 11 n , lat. ,'5,5 — 5^, 

 chronialophorum unicum parietale, ut videtur pyrenoide instructum, continentes. 

 Sporangia diametro c. 4 fjt. 



ScHMiTZ has established a genus Erythropeltis (189(i p. 'M3), which in its re- 

 j)roduction agrees with the genus Erylhrotrichia bul diflers from it by the frond 

 consisting only of a monostromatic disc with continuous border and with marginal 

 growth. To this genus is only referred one species, E. discigera (Berth.) Schmitz', 

 and to the same species Batters has later referred a new variety, var. Flustrce, 

 (Journ. of Bolany, Vol. 38, 1900 p. 376). The thallus is described in this as "orbi- 

 cular, becoming confluent and irregular in outline", and it must therefore be supposed 

 that the irregularity only appears by the fusion of originally separate discs. In our 

 plant, on the contrary, the frond consists of mutually separate filaments which only at 

 a later stage are paitly confluent, and it must therefore be referred to a new genus. 



The plant of which a diagnosis is given above was found in rather great 

 numbers on some specimens of Pohjsiphonia urceolata dredged off Hirshals in the 

 Skagerak. It forms irregular spots of up to 100 f/ in diameter on the surface of 

 the host-plant. It consists at first of branched filaments whose branches are mutu- 

 ally entirely separate. As shown in fig. 11 A the primary filament grows out in 

 Iwo opposite directions and gives otT branches at both sides. These branches grow 

 out and branch further, and in the more developed plant the filaments are there- 

 fore radiating in all directions in the horizontal plane, and the filaments are then 

 more or less fused together in the central part of the frond. The filaments show 

 apical growth, and transverse walls appear only in the terminal cells, a natural 

 consequence of the filaments being lixed to the substratum. The branches usually 

 arise in the sublerminal cell, sometimes also in cells nearer the centre of the frond, 

 but the terminal cell is only very seldom ramified. The ramification is thus 

 strongly monopodial. Not seldom a number of consecutive cells each give oil" a 

 branch, now alternating, now secund. The outline of the plant is always more or 

 less irregular, some filaments growing longer than others. 



The cells contain a single chromatophore, the foriu and .structure of which I 

 have not been able to determine with certainty, as I have only had dried speci- 

 mens at my disposal. In several cases however it appeared to be undoubtedly 

 parietal, and I often saw a body which I tof)k to be a pyrenoid, though it was not 

 very distinct (fig. 12). 



from a cell in the continuity of the Ijranched filaments recall the genus Erythroeladia, but the plants 

 need further examination. None of the described species can apparently be referred to the genus 

 Erythroeladia. 



' The genus is founded on Erylhrotrichia diseigera Berth.; but, according to Berthold (1882 p. 25), 

 the disc in this species sometimes produces erect filaments, and it must therefore be supposed that 

 ScHMrrz has taken the species in a more restricted sense than Bf.hthoi.d. 



