EXPLANATION OF THE PLATES. 



PLATE XII. 



Fig. 1. Draparnaldia plumosa. Fig. 2. Draparnaldia repe- 



tita. 



PLATE XIII. 



Fig. 1. Draparnaldia glomerata. Fig. 2. Chcetophora dila- 

 tata. Fig. 3. Batrachospermum bombusinum. 



PLATE XIV. 



Fig. 1. Batrachospermum pulcherrimum. Figs. 2 and 3. Ba- 

 chospermum alpestre. 



PLATE XV. 



Fig. 1. Batrachospermum confusum. Figs. 2 and 3. Ba- 

 trachospermum rubrum. 



PLATE XVI. 



Figs. 1 and 2. Batrachospermum atrum. Figs. 3 and 4. 

 Thorea ramosissima. The latter copied from Kutzing, and 

 showing its capsular fructification. 



PLATE XVII. 



Fig. 1. A cell of Zygnema nitidum, showing the curiously con- 

 structed central organ with its radii ; the cruciform raphide- 

 like bodies, and the curved strings of the cytoblasts. 

 Figs. 2 and 3. The same, exhibiting the appearance of 

 the central organ subsequent to the removal of the radii. 

 Figs. 4 and 5. Filaments of a non-conjugating Zygnema 

 showing the inverted structure of the cells in certain spe- 

 cies of the genus. Fig. 6. Portion of Cladophora crispata, 

 showing the vascular network which connects the zoospores 

 in the early period of their formation. Figs. 7 and 8. 

 Exhibit the ringed apparatus, with which the reproductive 

 cells in the genus Vesiculifera are furnished ; as also the 

 sporangia and the vascular network. 



