COSMARIUM. 81 



. MiOROSPHiNCTUM, Nord. Tar. PARVJJLA, Wille. Plate XLIX, 



figs. 20, 21. 



Cells small, elliptic, one-half longer than wide, moderately 

 constricted, sinus narrow linear ; semi-cell subelliptic, apex 

 in vertical view broadly elliptic, granulate within the margin, 

 center nude ; in lateral view suborbicular, end truncate. 

 Diameter of cell 25 p. ; length 33 n. 

 Tewksbury, Massachusetts. 



C. MARGARITIFERUM, Menegh. Plate XVI, figs. 1-3. 



Cells about one and one-half times longer than broad, sinus 

 narrow, usually more or less enlarged outwardly; semi-cells 

 semiorbicular, somewhat reniform or oval, with rounded in- 

 ferior angles, convex sides and broadly rounded, not truncate 

 end. Cytioderm rough with pearly granules ; end view 

 elliptic ; zygospores orbicular. 



Diameter 25-50 ^. 



This species varies in size and form. The rough membrane 

 distinguishes it from C. crenafui and C. undulation ; its 

 rounded ends from C. Uotrytis, its smaller size and less posi- 

 tive kidney form from C. r< nij'ormc. It appears to be as 

 widely distributed as the most common of this genus. 



C. PUNCTULATUM, Breb. Plate XVI, fig. 4. 



This form is very similar to C. inarf/aritiferutn, but it is 

 smaller, the pearly granules less conspicuous, aud the ends 

 more flattened. The membrane is sometimes not granular, 

 but punctate. It is found in the same localities, and appears 

 very nearly related. 



Diameter of cells 20-30 /<. 



. POLYMORPHUM, Nord. Plate XLIX, figs. 31-33. 



Suborbicular, deeply constricted, sinus narrow linear ; 

 semi-cells semicircular, base straight, ends truncate; two 

 granules above the base, three about the middle of the area ; 

 punctate between the two series ; granulate near the margin ; 

 in vertical view broadly elliptic, granulate within the mar- 

 gin, center nude; in lateral view suborbicular, end truncate. 



Diameter of cell 25 //. ; length 33 >u. 



C. BOTRYTIS, Menegh. Plate XVI, figs. 5-7. 



Cells one, and nearly two times as long as broad ; sinus 

 narrow linear ; semi -cells with nearly straight base, some- 

 times inclining to reniform ; sides converging from the iu- 



6 



