COSMAEIUM. 96 



Reminds one of C. ornatum, Foeke, and also of C subreni- 

 foriDe, Nord. 



Tewksbury, Massachusetts. 



0. Blyttii, WiUe. Plate XXII. figs. 31,' 32, 33. 



Small, somewhat longer than broad; semi-tells subreni- 

 form, apex truncate with four crenulations ; sides erose- 

 crenate fcrenae three); semi-cells within the margin, granu- 

 late, granules arranged in two series of about fourteen and 

 nine ; in center a small prominence. Lateral view circular 

 with a papilla on each side ; end view elliptic, with a promi- 

 nence or papilla on each side. 



Diameter 14-15 /^. ; length 17-18 ju. 



Waters of Sussex County, N. J. ; Longwood Pond ; Wood 

 Lake. 



0. SPECIOSUM, Lund. Plate XXII, figs. 7, 8, 9; 14, 15. 



Cells about one and one half times longer than wide ; 

 elliptic-oblong, constriction forms a narrow linear sinus ; 

 semi-cells with sides slightly convex, but moderately converg- 

 ing to the subtruncate end ; inferior angles nearly square, 

 base plane ; margins crenate, crenae eighteen ; within the 

 margins granulate; granules arranged in regularly radiating, 

 and concentric series ; at the base seven to eight vertical 

 series of smaller granules ; viewed from the vertex elliptic 

 with a central inflation, ends crenulate ; lateral view sub- 

 ovate ; thickness 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 /<. ; length 50-75 /*. 



The plants recognized as the C. speciosuni of Lundell, are 

 usually larger than the Swedish forms, but they have the 

 same outline, truncate end, swollen centers, arrangement of 

 granules and crenulate margins. 



C. suPEASPECiosuM, Wollc. Plate LXI, figs. 5, 6. 



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 semf- 

 cell ; usually about sixteen on each side and five or six on 

 the truncate 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 



