EXPLANATION OF PLATES. 



PLATE I. 

 J. H. Blake and W. G. Farlow. 



Fig. 1. Glceocapsa crepidinum, Thuret. 600 diam. 



2. Isactis plana, Thuret. 600 diam. 



3. Splmrozyga CarmichaelU, Harv. : a, heterocyst ; b, b, spores. 600 diam. 



4. Lyngbya majuseula, Harv. 400 diam. 



5. Oscillaria aubuliformis, Harv. 500 diam. 



6. Calothrix confervicola, Ag. : a, a, hormogonia ; b, b, heterocysts ; c, cell of host- 



plant. 400 diam. 



PLATE II. 

 J. H. Blalce and W. G. Farlow. 



Fig. 1. Hormactis Quoyi, (Ag.)Bornet: a, a, heterocysts. 600 diam. 



2. Rivularia atra, Roth : a, a, heterocysts ; the cross-lines represent the gelatinous 



matrix. 500 diam. 



3. Microcoleus chthonoplastes, Thuret: a, free trichomata projecting beyond the 



ruptured sheath. 500 diam. 



4. Spirulina lenuissima, Kutz. 900 diam. 



PLATE III. 



J. H. Blalce and W. G. Farlow. 



Fig. 1. Viva Lactuca, (L.) Le Jolis: a, microzoospores which have escaped from mar- 

 ginal cells ; b, cells in which zoospores are forming ; c, cells from which zoo- 

 spores have escaped. 500 diam. 



2. Rhizoclonium riparium, Kutz. 20 diam. 



3. Cladophora lartevirem, (Dillw.) Harv. 20 diam. 



PLATE IV. 



J. H. Blalce and W. G. Farlow. 



Fig. 1. Bryopsis plumosa, (Huds.) Ag. ; portion of upper division of the unicellular 

 frond. 10 diam. 



2. Vaucheria Thuretii, Woronin : a, a, young antheridia; a', antheridium which 



has discharged its antherozoids ; c, c, oogonia with oospores. 100 diam. 



3. PhyllUis fascia, Kiitz ; section of frond with plurilocular sporangia, a, cover- 



ing the surface. 500 diam. 



4. Derbesia tenuwzima, (De Not.) Crouan : a, spores (zoosporangia ?) nearly mature ; 



b, V, cross-partitions forming cell at base of sporangium. 100 diam. 



5. Pivnctariaplantaginea, (Roth) Grev. ; transverse section of frond : a, plurilocular 



sporangia with zoospores ; a', the same when old, after the zoospores have 

 been discharged and the internal cell-walls obliterated. 



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