158 DESMIDS <)F THE UNITED STATES. 



Docidium (Pleurotaenium) breve, Wood. (Add to page 30). 

 Robust, 48 times longer than broad, distinctly constricted, 

 but not undulate in the middle; slightly attenuated towards 

 the ends; apex truncate and somewhat rounded; cytioderm 

 very thick, densely minutely granulate ; margins either 

 straight or shortly undulate. 



Diameter 20-24 //. 



Dr. Wood remarks, " this species was sent to me by Dr. 

 Billings, who obtained it near Washington, D. C. The 

 margins are sometimes straightish, but in other fronds there 

 are three or more distinct, short, undulations or rounded pro- 

 jections in each half margin." 



The shape of the semicell is very near Plate X, fig. 12, 

 but only about half the size, not so undulate and not spinous. 



Closterium SUBTILE, Breb. Plate VII, tig. 2. (Add to page 40). 

 ( \ lis very slender, acieular, slightly curved, narrow lan- 

 ceolate, apices acute, cuspidate. 

 I diameter 34 >>.. 



Pond-. N< u Jersey, rather rare. 



C. pseudogranatum, Nbrd. Plate XVII. figs. 21-23. (Add to 

 page 80). 

 This plant differs from C. granatum, Breb. in having a dis- 

 tinct central Inflation as is evident in lateral and transverse 

 views. Unlike C. granatum, and unlike the Brazil plant de- 

 scribed by Nord., the sides of the semicells are not sinuate or 

 straight, but somewhat convex. Membrane punctate. 

 Diameter 35 ".\ length 60 n. 



Pond. Northampton County, Pennsylvania. 



Cosmarium TURPINII, Breb. Plate XVII, tigs. 24,25. (Add 

 to page si ). 

 Cells of equal length and breadth; constriction deep, tonus 

 a narrow linear or acute-angled sinus, outwardly ampliated ; 

 semicells triangular, lower angles rounded, apex truneately 

 rounded ; sides somewhat concave; central inflation granulate, 

 and sometimes emarginate : cytioderm finely granulate or 

 punctate. 



Diameter 55-70 //. 



Not rare ; frequently in large numbers in ponds, New 

 Jersey, Pennsylvania and many other States. 



