42 DK8M1DS OF THE UNITKD STATES. 



SKCTIOS II. Cells slightly bent, the imck idnrsumi more or less convex, tin- op- 

 posite (ventral) side almost straight, distinctly attenuated from the middle to tin- 

 ends. Zygospore globular, smooth. 



C. LUNULA, Ehrb. Plate LXI, fig. 26. 



Cells large, seniilunar, 5-(> times longer than broad, 

 smooth, or very finely striate, indistinct, back high convex, 

 lower side straightish, ends attenuated, rounded. Chloro- 

 phyl globules numerous; vacuole usually distinct and con- 

 tains many actively moving granules. 



Diameter 80-110 /*. 



Frequent in small ponds. 



The figure is not a good typical form. It should not be 

 curved so much at the end. 



Var. STRIATUM, Wolle. 



Differing from the ordinary form by having the cytioderm 

 finely, but distinctly striate. 



. CUCUMIS, Ehrb. Plate VII, figs. 17, 18. 



Cells smooth, stout, semilunate ; ends broadly rounded. 



Ehrenberg's figure represents this species about five times 

 longer than broad ; in form somewhat resembling C. Lunula, 

 not so large, and lower side more concave. Ehrenberg col- 

 lected it in the State of New York. The figures are from 

 plants found in New Jersey and Pennsylvania. They are 

 evidently closely allied to C. Lunn/n. 



C. SUBTILE, Breb. Plate VIII, fig. 2. 



Cells very slender, acicular, slightly curved, narrow lan- 

 ceolate, apices acute, cuspidate. 

 Diameter 3-4 >u. 



Ponds, New Jersey. Rather rare. 



. ACEROSUM, (Schrank), Ehrb. Plate VII, figs. 7, 11. 



Linear fusiform or slightly curved, 15-24 times longer 

 than wide, lightly tapering towards the ends ; apices nar- 

 rowly truncate, or obtusely rounded, transparent or yel- 

 lowish; cytioderm rather indistinctly, or not at all striate. 

 Chlorophyl globules 11-14 arranged in a simple axillary 

 series in each semi-cell ; vacuole small with numerous cor- 

 puscles. Zygospore globose, or broadly elliptic. 



Diameter variable, 35-G2 u. 



Plate X, figs. 1, 2. A specimen finely in fruit ; presenting 

 the peculiarity of two forms of zygospores, single and twin, 

 oval, the longer axis at right angles with the axis of the 

 cells. Cell walls finely but distinctly striate. 



