88 DESMIDS OF THE UNITED STATES. 



ing to the subtruncate end ; inferior angles nearly square, 

 base plane; margins crenate, orenae eighteen; within the 

 margins granulate ; granules arranged in regularly radiating, 

 and concentric series ; at the base seven to eight vertical series 

 of smallar granules ; viewed from the vertex elliptic with a 

 central inflation, ends creniilate; lateral view subovate ; thick- 

 ness of cells about one-half of the diameter of the cell ; 

 isthmus equal to about one-third of the measure of the breadth. 

 Diameter 33-50 u.\ length 50-75 u. 



The plants recognized as the ('. speciosiim of Lundell, are 

 usually larger than the Swedish forms, but they have the 

 same outline, truncate end, swollen centres, arrangement of 

 granules and crenulate margins. 



< . SUPRASPECI08UM, W'olle. Plate L, figs. 5, <). 



Large, broadly oval, about one-third longer than broad, 

 ends truncate ; deeply constricted ; isthmus rather less than a 

 third part of the breadth of the cell; sinus narrow linear ; 

 margins crenulate with thirty or more crenae to each semicell; 

 usually about sixteen on each side and five or six on the trun- 

 cate end ; ornate with large undivided granules arranged in 

 concentric and at the same time, radiating series, extending 

 from the margin nearly half way to the centre; central area 

 nude except live or six vertical series of smaller granules ; end 

 view shows a prominent central inflation ; lateral view broadly 

 ovate, sinuate towards the end-. 



Diameter 65-70 yu.; length 90-95. 



Occurs frequently in ponds, northern New Jersey and in 

 Pennsylvania. 



C. Pect|n(iiks, Wolle. Plate XIX. figs. 12, 13. 



Suborbicular, somewhat longer than broad, constriction deep, 

 sinus narrow linear within and widening outwardly ; semi- 

 cells semiorbicular with the angles rounded, undulate on the 

 margins with twenty or more crenulations ; rough with 

 geminate rows of pearly granules symmetrically arranged in 

 radiating and concentric lines. On green cells the united 

 twinned granules appear oblong and the crenulations dentate; 

 at the base of the semicells the inflation is marked with six, 

 more or less distinct, vertical series of .-mailer granules; end 

 and side view evidence a distinct basal protuberance. 



