56 



]. Bamjiea'. Gonidia arising by division (or also witliout division) 



from an originally vegetative mother-cell. 



Frond filiform Banyia. 



Frond Hat Porphijra. 



2. Erythrnirichiciv. Gonidia arising in special monosjjornngia, cul otT 

 by a curved wall in a vegetative cell. 



Frond eiecl, filiform Erythrotrichia. 



Frond first cushon-like, thereafter vesicular, ruptured and ex- 

 panded in a monostromalic plane Porphyropsis. 



Frond consisting of creeping branched filaments, more or less 



confluent to a monostromalic disc Erythrocladia. 



(Frond a monostromalic parenchymatous disc Erythropeltis). 



ii. Gonioirichieci'. Gonidia arising v^'ithoul cell-division. 



Gonidia naked Goniotrichum. 



Gonidia provided with cell-wall Asterocytis. 



Bangia Lyngb. emend. 

 1. Bangia fusco-purpurea (Dillw.) Lyngb. 



Lyngbyk Hydr. p. 83, tab. 24 C; Hakvuv Pliyc. Hrit. pi. 96; Rrinke in Pi iiiKsh. .lalirb. 9. Hd. p. 274 tab. 12; 



Berthoi.d (1882) fig. 12-14; Kylin (1907) p. 107. 

 C.onfenui fusco-piirpiiren Dillw. Brit. Conf. pi. 92. 



lUuujia (itro-purpuiea (Hotiii ^J, fiisco-purpurea (I)ilUv.) Ag. Syst. p. 7(1; Fl. Dan. tab. 1841; J. Agardii 

 (188;i) p. 36. 



In l<SO(i Roth described (Calal. hot. Ill p. 208), under the name of Conferva 

 (tiro-purpureu, a filamentous Alga found in a water-mill at Bremen; it was referred 

 lo the genus Bangia by Lyngbye and was found in similar localities at many other 

 places in Europe. Three years later, Dillwyn described a somewhat similar species, 

 B. fusco-purpurea, first found on the British shores, and largely distributed on the 

 x\tlantic and Mediterranean shores. The resemblance between the two species, 

 however, was so great, that Lynm.bye referred Roth'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 

 .1. Agardh, who, however, expressly distinguished the freshwater form from the 

 marine form while the older Agaudh 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 Dillwyn's name. The distri- 

 bution of the species on the Danish shores does not favour the supposition of a gradual 

 transition to the freshwater form, as it does not occur in water of low salinity. 



The plant is at fii'st a filament consisting of a single low^ of cells, and fixed 

 at the base by rhizines, which grow downwards from the lower cells in the 

 common outer-wall (Reinke 1. 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. 



