TETRASPORA. 191 



Syn. Ulva bullosa, Roth. ; Tetraspora minima, Desv. ; Monotrema 

 bullosiim, Thur. 



In sluggish, shallow streams, attached to stones. 



Plate CLXV, figs. 1-6, three forms ; 1-4 about natural 

 size ; fig. 5, about half, or quarter natural size ; fig. 6, the 

 cells magnified. 



TETRASPORA LUBRICA, (Roth. ) Ag. 



Thallus elongated, tubular, erect, two to twelve inches 

 long; splitting, undulate, sinuous, between gelatinous and 

 menibranaceous, yellowish green, cells globose, or somewhat 

 angular, green, tegument very thin. 



Diameter of cells, 8-10 yw. 



Syn. Ulva lubrica, Roth ; Tetrasporella lubrica, Gaill. 



In rather quiet spring water, sometimes in large quantity. 

 Plate CLXV, fig. 9, only about half the natural size. 



Var. LACUNOSA, Chaud. 



Thallus elongate, tubular, but not erect, attached to stones, 

 in not rapid mountain streamlet, light green, thallus numer- 

 ously perforated, with large elliptical lacunae. Thallus 

 2-10 inches long. 



Plate CLXV, fig. 10, thallus half natural size ; fig. 11, 

 cells magnified. 



TETRASPORA GELATINOSA, (Vauch.) Desv. 



Thalli large, irregularly expanded and divided, very gela- 

 tinous, at first attached, then swimming free, colorless or 

 edged with green; cells spherical, scattered or by twos; 

 variable in size. 



Diameter of cells, 3-12 yw. 



Mountain springs, Broadtop Mountain, Pennsylvania. 

 All the masses with scattered filaments of Oscillaria cruenta. 



TETRASPORA EXPLANATA, (Kg. ) Kirch. 



Thallus attached, or floating ; irregularly expanded, 

 rather soft and slippery, green; cells somewhat elliptic, 

 angular, or globose, usually small and by twos. 



Diameter of cells, 5-7 /*. 



The form recognized as of this variety most frequent on 

 wet timbers about sluices at mills. 



Syn. Palmella terminates, Ag. ; Coccochloris terminates, Breb. 



Plate CLXY, fig. 12, most frequent form, less than natural 



size. 

 13 



