28 DESJflDS OF THE UNITED STATKS. 



Genus, PHYMATODOCIS, Xord. 

 Cells closely united in sheathless filaments, not at all or only 

 slightly twisted ; cells deeply constricted in the middle, the two 

 semi-cells somewhat twisted, giving the margins an irregular 

 outline; filaments quadrangular with sides longitudinally ex- 

 cavated. 



P. XOEDSTEDTIANUM, Wolle. Plate LX, figs. 1-4. 



Cells rectangular, about as long as wide, deeply constricted 

 in the middle, the sinuses somewhat enlarged inwardly and 

 rounded at the base ; the sinuses between the cells similar, 

 slightly deeper ; end view quadriradiate with wide and deep 

 sinuses between the rays, apices rounded, emarginate ; the 

 two semi- cells somewhat twisted, so that the end of one ray 

 projects more than that of the other and produces an irreg- 

 ular outline ; membrane smooth. 



Diameter 37-4:0 /J. 



This new species in ponds at Brown's Mills and Egg Harbor, 

 Xew Jersey, and at Kissimme, Florida, differs from the form 

 collected in Brazil, in being one-fourth smaller ; in havings 

 the lobes or rays in end view straight, not curved to one side, 

 and in having the sinuses of the cells not narrow linear, but 

 somewhat enlarged inwardly and rounded at base. 



Genus, SPHAEEOZOSMA, Corda. 

 Plate IV, figs. 1-16. 



Cells closely united side to side by a narrow isthmus or by 

 means of glandular processes, deeply incised on each side, thus 

 forming bilobed cells, and often giving a pinnatifid appearance 

 to the fragile filaments. 



Filaments often surrounded by a colorless gelatinous en- 

 velope. 



Brebisson separated the forms which have the cells united 

 without glandular processes with a new genus Spondtlosum. 

 The distinction is hardly tenable. The modes of union, like the 

 gelatinous sheaths, are inconstant, hence should not be made- 

 generic or specific characteristics. 



This genus differs from the preceding in the compressed, flat, 

 not round, triangular nor square filaments, but deeply incised 

 cells, and especially in the frequent i^resence of the minute gland- 

 like connecting processes. 



