114 



sometimes proportionally much developed (fig. 41), but like Kylin I found it al- 

 ways consisting of one layer of cells, while Pringsheim (Beitr. Morph. Meeresalg. 

 p. 26 Taf.VII fig. 2), Borgesen and Collins (1906 p. 194) found it consisting of two 

 or several layers. 



While this form in its typical shape is quite distinct from the typical f. lux- 

 urians, intermediate specimens may sometimes occur, hi my opinion it is a re- 

 duced form of the species produced by growing near the low-water mark, where it 

 may sometimes be exposed to the air. On the Danish shores it has only been 

 found at the low-water mark, on the west coast of Jutland even at a higher level. 

 It has been found growing on Porphyra umbilicalis, Sertularia pumila, Chcetomorpha 

 Melagoniiim and Polysiphonia nigrescens, in the months January to August. 



Localities. Ns: Esbjerg; groin no. 62 by Tiiyboron. Sk: Hirshals mole. — Lf: Hals. — 

 Kli: Frederiksliavn, harbour (!, Th. Mortensen, C. H. Ostenfeld). 



11. ( haiitransia Macula sp. nov. 



Thallus minutus membranaceus monostromaticus fere orbicularis, diametro 

 usque c. 70 //, substrato adhaerens, initio parenchymaticus; dissepimentum primum 

 medianum , sequentia obliqua ; postea cellulse marginales in fila repentia plus 

 minus radiantia excrescunt. Cellulse c. 4 fj. crassse, diametro sesqui- ad duplo 

 longiores, chromatophorum stellare pyrenoide cenirali instructum continent. Fila 

 erecta sparsa brevissima paucicellularia simplicia plerumque e disco egrediuntur. 

 Pili hyalini in fills radiantibus erectisque terminales hinc illinc occurrunt. Spor- 

 angia monospora in disco sessilia vel in fills erectis terminalia, ovata, long. 10 — 

 11,5 fi, lat. 6,5 — 7 ft. 



This very small species has been found growing on Polysiphonia violacea to- 

 gether with several other species of Chantransia. It is very characteristic from its 

 thin disc-shaped frond of an irregular outline, approaching however the circular, 

 and corresponding to Ihe basal layer of the more developed species, while the erect 

 filaments are wanting or much reduced. The germinating spore divides always by 

 a median vertical wall, and oblique walls then appear in the two daughter-cells, 

 frequently resulting in the formation of two inner, triangular and four outer cells 

 (fig. 42 A, B, F). The orientation of the walls may be somewhat variable, but in 

 the central part of the more developed discs one or two triangular cells are usually 

 recognizable, thus indicating the place of the first division wall. In some cases 

 one of the primary daughter-cells only is divided by oblique walls (fig. 42 D), and 

 more rarely both cells are divided by a wall parallel to the first. The plant keeps 

 for some time its parenchymatous character and a fairly regular outline, often up 

 to the eight-celled stage, but then the marginal cells begin to grow out into creep- 

 ing filaments which from the first may be rather irregular but later by the increa- 

 sing number become more regularly radiating, forming a pseudoparenchymatous 

 disc with irregular border formed by the separate ends of the filaments. The 



