56 
1. Bangiee. Gonidia arising by division (or also without division) 
from an originally vegetative mother-cell. 
Frond fi fon see cee 2 ne Te Ce Bangia. 
Frond flatts qa See EE CL Ge OC EL LES Porphyra. 
2. Erythrotrichiee. Gonidia arising in special monosporangia, cut off 
by a curved wall in a vegetative cell. 
EronderecEstilrfo rr me RE re EE PT EC LS Erythrotrichia. 
Frond first cushon-like, thereafter vesicular, ruptured and ex- 
panded in a monostromatic plane ......................... Porphyropsis. 
Frond consisting of creeping branched filaments, more or less 
CON MAN TO AMOTCSROTAUMNEC ChSEe EM eee po oc Erythrocladia. 
(Frond a monostromatie parenchymatous dise................ Erythropeltis). 
3. Goniotrichieæ. Gonidia arising without cell-division. 
Gonidiannaked 5575 S80: CARR REP N ARTE CPR Goniotrichum. 
GonidiasproyadedSwilhzeellwalleegee pe cri ES SER ae Asterocylis. 
Bangia Lyngb. emend. 
1. Bangia fusco-purpurea (Dillw.) Lyngb. 
LYNGBYE Hydr. p. 83, tab. 24 C; Harvey Phye. Brit. pl. 96; REINKE in Pringsh. Jahrb. 9. Bd. p. 274 tab. 12; 
BERTHOLD (1882) fig. 12—14; Kyrın (1907) p. 107. 
Conferva fusco-purpurea Dillw. Brit. Conf. pl. 92. 
Bangia atro-purpurea (Roth) /, fusco-purpurea (Dillw.) Ag. Syst. p. 76; Fl. Dan. tab. 1841; J. Agardh 
(1883) p. 36. 
In 1806 Rorx described (Catal. bot. III p. 208), under the name of Conferva 
atro-purpurea, a filamentous Alga found in a water-mill at Bremen; it was referred 
to the genus Bangia by LYNGBYE and was found in similar localities at many other 
places in Europe. Three years later, DirLwyn described a somewhat similar species, 
B. fusco-purpurea, first found on the British shores, and largely distributed on the 
Atlantic and Mediterranean shores. The resemblance between the two species, 
however, was so great, that LYNGBYE referred Rorn’s species as a variety to B. 
fusco-purpurea, while C. AGARDH conversely regarded B. atro-purpurea as the main 
species and B. fusco-purpurea as variety. The latter view was also maintained by 
J. AGARDH, who, however, expressly distinguished the freshwater form from the 
marine form while the older AGARDH only took the colour into consideration. I 
shall not enter on the question of the relation of these species, but like most of the 
marine phycologists record the marine species under Dittwyn’s name. The distri- 
bution of the species on the Danish shores does not favour the supposition ofa gradual 
transition to the freshwater form, as it does not occur in water of low salinity. 
The plant is at first a filament consisting of a single row of cells, and fixed 
at the base by rhizines, which grow downwards from the lower cells in the 
common outer-wall (REINKE |. c. fig. 1). In this form the plant can attain a con- 
siderable size, but sooner or later longitudinal walls occur, which have a more or 
less radial position and which divide the articles into wedge-shaped cells. 
