CLOSTERIUM. 49 



There appear to be two varieties of this species ; one with 

 rather broad truncately rounded ends ; the other, smaller 

 with more pointed ends. 



Georgia; Rhode Island; (Bailey). Pennsylvania and New 

 Jersey; occurs frequently. 



C. LEIBLEINII, Kg. Plate VIII, figs. 13 and 20. 



In outline bears a strong resemblance to the two preceding, 

 but is shorter, stouter, upper margin more convex and ends 

 more acute ; lower margin concave with a central inflation. 

 Diameter 40-60 /<. 



Found in ponds with the two preceding. 



Var. CURTUM, West. Plate XLIII, fig. 22. 



Differs from the typical form by its shortened ends. Has 

 the appearance of a miniature C. Ehrenbergii. 

 J. R. M. 8., Nov., 1888. 



. RALFSII, Breb. Plate VIII, fig. 10. 



Stout, finely and densely striated, curved, rapidly attenu- 

 ated into somewhat linear beaks which are shorter than the 

 ventricose body ; 6-8 times longer than broad. 

 Diameter 42-47 /<. 



Pond near Perth Amboy, New Jersey. 



Color of this species changes from green to a yellow brown ; 

 the upper margin is convex, the lower concave but ventricose 

 at the center; chlorophyl vesicles rather irregularly disposed 

 in a single row : a transverse suture is usually evident in the 

 middle. 



SECTION V. Cells more or less curved, ventral margin also somewhat inflated, 

 but the end drawn out into beak or seta-like extensions. Zygospores angular. 



C. ROSTRATUM, Ehrb. Plate IX, figs. 1, 2. 3. Plate XLIII, 



fig. 21. 



Lanceolate-fusiform, ends thin, drawn out to nearly half 

 the length of the body ; cytioderm light yellowish, densely 

 but finely striate; chlorophyllous vesicles and vacuoles 

 usually indistinct; the latter when seen has 12-15 actively 

 moving corpuscles. 

 Diameter 23-40 /<. 



Var. BREYIROSTRATUM, West. 



Differs from the usual form in its short and less attenuated 

 ' beak. 

 4 



