28 DESMIDS OF THE UNITED STATES. 



Genua, PHYMATODOCIS, Nord. 



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 out- 

 line; filaments quadrangular with side- longitudinally excavated. 



P. \<>!:iT KDTIANI M , W'olle. Plate XLIX, 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, 

 Blightly deeper ; end view quadriradiate with wide and deep 

 sinuses between the ray-, apices rounded, emarginate; the two 

 semi-cells somewhat twisted bo that the end of one ray projects 

 more than that of the other and produces an irregular outline ; 

 membrane smooth. 



Diameter 87- I" ". 



This new Bpecies, hitherto found only in pond at Brown's 

 Mill-, New Jersey, differs from the form collected in Brazil, 

 in being one-fourth Bmaller; in having the lobes or rays in 

 end view Btraight, Dot curved to one Bide, and in having the 



sinuses of the cells nut narrow linear, Imt somewhat enlarged 

 inwardlv and rounded at base. 



Genua, SPHAERt >/' NSMA, < orda. 

 Plate IV. figs. 1-16. 



( Jells closely united Bide to side by a narrow isthmus or l>v means 

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

 bilobed cells, and often givinga pinnatifid appearance to the fragile 

 filaments. 



Filaments often surrounded by a colorless gelatinous envelope. 



Brebisson separated the forms which have the cells united with- 

 out glandular processes with a new genus Spondylosum. The 

 distinction i- hardly tenable. The modes of union, like the 

 gelatinous -heath-, are inconstant, hence should not be made generic 

 or specific characteristics. 



This genus differs from the preceding in the compreaaed, flat, not 

 round, triangular nor square filaments, but deeply incised cells, and 

 especially in the frequent presence of the minute -land-like con- 

 necting pro i - 



