94 DESMIDS OF THE UNITED STATES. 



length ; margins scolloped or broadly crenate, with four cre- 

 natures at the end, one on each side at the base, and one 

 intermediate between it and the end ; the lateral, basal ones 

 are the largest ; membrane sulcated between the crenatures ; 

 rough with pearly granules ; end view oval, somewhat in- 

 flated at the middle. 



Diameter 40 yw., more or less. 



A distinct species which turns up frequently in smaller 

 numbers. 



C. QUADRIFARIUM, Lund. Plate XX, figs. 16, 17, 18. 



About one-fourth longer than broad, deeply constricted, 

 sinus narrow linear ; semi- cells, semicircular; inferior angles 

 nearly right; margin composed of 17 emarginate-truncate 

 verrucae : within the margin a similar series ; basal tumor 

 orbicular, furnished with 12-17 larger granules ; viewed 

 from the vertex, elliptic, with a granulated tumor on the 

 middle of each side, and four series of granules extending 

 from end to end ; lateral view has a granulated swelling on 

 each side and four granules on the end terminating four 

 series. Two chlorophyllous nuclei in each semi -cell. 

 Diameter 33-36 //. ; length 40-44 yu. 



Frequent in ponds, Mt. Everett, Mass. 



C. KJELLMANII, Wille. Plate LX, figs. 19, 20, 21. 



Nearly equal in length and breadth, deeply constricted in 

 the middle, sinus linear with mouth considerably ampliated; 

 semi-cells cordiform, sides nearly straight, or low convex ; 

 apex truncate with four or six light crenulations ; the sides 

 each with six indentations; granules arranged in radiating 

 lines, none in the center, but a basal tumor has five vertical 

 series of granules; observed from the vertex the semi-cells 

 are narrow elliptic, with a tumor on each side. 



Diameter 20-25 ^. 



Wood Lake, Sussex County, New Jersey. 



C. SUBCRUCIFORME, Lagh. Plate XLIX, figs. 12-14. 



Small, somewhat circular, the constriction introrsely and 

 extrorsely ampliated ; semi-cells reniform, the end rounded, 

 not crenulate; angles rounded verrucose with margins den- 

 ticulate; a central inflation granulate; in vertical view 

 subcruciform, angles 'granulate ; in lateral view ovate-cir- 

 cular. Membrane punctate. 



Diameter of cell 32 //. ; length 36 //.; thickness 25 //. 



