SPIROTAENIA. 33 



M. CLEPSYDRA, Wood. Plate III, figs. 12-15. 



Living on rocks and mosses, swimming in a transparent, 

 sometimes light-green jelly; cells obtusely truncated, 

 rounded at the ends, 2-3 times longer than broad ; chlorophyl 

 lamina axillary, mostly indistinct, often wanting ; endochrome 

 light green ; nucleus generally distinct ; zygospores subfuscous, 

 either globose or of an irregular form, somewhat resembling 

 that of an hour-glass ; external coat irregularly excavated 

 and sulcate. 



Diameter given by the author is rMu"? this would be .00173 

 = 43 p. Evidently an. error, the plant cannot be so large. 



The author adds, "This species was found near Chelten 

 Hills, growing amid mosses on the rocky juttings over which 

 the water was dripping. It occurs as a rather firm, transpa- 

 rent jelly, mostly of a light greenish tint, in which the cells 

 are often placed quite thickly. 



Genus, SPIEOTAENIA, Breb. 

 Plate III, figs. 16-22. 



Cells straight fusiform, single or aggregated in a gelatinous 

 mucus ; not constricted in the middle, ends round. Chlorophyl 

 arranged in one or more spiral lamince on the inner surface of 

 the wall. 



S. CONDENSATA, Breb. Plate III, figs. 21, 22. 



Fusiform, or cigar-shaped, ends rounded, eight to ten 

 times as long as broad, with a single, broad, closely wound 

 chlorophyl spiral band, its revolutions numerous. 

 Diameter 18-25 //. 



Found in meadow pools, ponds, etc. Has been collected in 

 many States of the Union, from New York and New Jersey, 

 south to Florida, and westward to Minnesota. 



S. OBSCURA, Ealfs. Plate III, figs. 16-19. 



Fusiform, deep green, five to eight times longer than broad, 

 ends attenuated, apices rounded. Chlorophyl arranged in 

 a number of narrow spiral, parietal bands. 



Diameter 8-15 /*. 



The locality in which this species occurred most frequently 

 to me, was in small pools aside streamlets on the open slope 

 of our mountain sides, but found it also in New Jersey. 

 European specimens are quoted as large as 30 ,". in diameter. 

 I have found none so large. 

 3 



