KXPLANATION OF PLATES. 



PLATE I. 



1. A single filament of Oscillaloria chlorina, Kiitzing, magnified 750 diameters. 



. 2. The end of a filament of an Oscillaloria supposed to bo identical with 0. Frolilichii 



Kiitzing. 



Fiir. 3. O. nigra, Vaucher. 



l-'iir. 3 a. Represents a portion of a mat or mass of Oscillaloria nigra, Vauchcr; there is too 

 much irrri'ii in the color. 



." li. lli-prcsents several filaments separated from the edge ofljie moss and slightly magni- 

 led 



Fig. 3 c. A portion of a Filament. 



Fiir. 3 d. A portion of another filament still more highly magnified. The color in 3 c is more 

 natural than that of 3 d. 



Fig. 4. A portion of a filament of 0. limosa, Agardb, magnified 1250 diameters. The articles in 

 this filament are more distinctly separated than natural. 



Fig. 5. 0. neglecla, Wood. 



Fig. 5 a. An outline view of a filament, magnified 450 diameters. 



Fig. 56. A full figure of the same, magnified 500 diameters. 



Fig. 6 0. imperalor, Wood. 



Fiir. 6 a. Represents the end of a filament, magnified 250 diameters. In the centre of the plate 

 is a fragment (marked simply fig. 6.), oat of which the endochrome has been partially squeezed to 

 show the markings of the sheath at the joints. 



Fig. 7. Lyngbya bicolor, Wood. Fig. 7 represents a moderately magnified portion of a filament. 

 Fig. a (near to fig. 8) represents a portion of an ordinary filament very slightly magnified. 

 Fig. 7 c. A portion of a filament containing a heterocyst, magnified 800 diameters. 

 Fig. 7 d. A broken end of a filament showing the sheath extending beyond the endochrome, 

 magnified 800 diameters. 



Fig. 8. A varicty(?) of Lynybya bicolor, Wood, from the Schnylkill River, magnified 200 dia- 

 meters. 



Fig. 9. Coamarium Quimbyii, Wood. The bands between the cells are too heavy and prominent 



PLATE II. 



Figs. 1 6 and 1 c. Different stages of germination of the spore of a Cylindrospermttm of unknown 

 ipecies, magnified respectively 800 and 1200 diameters. 



Fig. 1 a. A chain of spores, believed to belong to the same species; one of these spores has 

 commenced to germinate. 



Fig. 2. A portion of the upper surface of a frond of Nostoc calidarittm, Wood. 



(253) 



