222 TUFTS COLLEGE STUDIES, VOL. II, No. 3 



longitudinal and horizontal series. Figs. 78, 79. Greenland, 

 Alaska. 



Borgesen, 1902, p. 482, includes Gayella in Prasiola crispa as 

 subspecies maiina. It is certainly hard to draw the line be- 

 tween Prasiola, Schizogonium and Gayella ; but the habit of Gay- 

 ella is so distinct from the other two genera, that until we have 

 definite evidence of the connection, it would seem better to 

 maintain the genus. 



Family 4. CYUNDROCAPSACEAE. 



Frond a monosiphonous, rarely partly polysiphonous filament, 

 at first attached, later free, composed of cells with parietal chro- 

 matophore and one pyrenoid ; asexual reproduction by zoospores 

 has been reported, but is not fully confirmed ; akinetes as in 

 Ulothrix ; sexual reproduction by antheridia and oogonia, 2-4 

 antheridia formed by division of a vegetative cell, each anther- 

 idium producing 2 spindle-shaped, biciliate, -yellowish spermato- 

 zoids, escaping through an opening in the side wall ; oogonium 

 formed from a swollen vegetative cell, containing one oospore, 

 fertilized by spermatozoids entering by an opening in the wall ; 

 fertilized oospore reddish, development unknown ; the unferti- 

 lized oospore may develop parthenogenetically, remaining green, 

 and dividing to form a new filament. Fresh water. Only one 

 genus. 



CYLINDROCAPSA Reinsch, 1867, p. 66. 



Characters of the family. 



In its vegetative characters Cylindrocapsa is nearly related to 

 Ulothrix, but in fructification it shows considerable resemblance, 

 and is the only alga having any considerable resemblance, to 

 the Oedogoniaceae. 



C. GEMINELLA Wolle, 1887, p. 104, PI. XCI, figs. 1-17; 

 P. B.-A., No. 570. Filaments 14-16 ^ diam. (or more ?) subtoru- 

 lose, with thick, distinctly lamellate wall ; oospore globose, 

 about 50 fji diam., lamellate wall about 10-15 M thick. In stand- 

 ing water, free or adhering to other algae. Fig. 80. Mass. ; 

 " N. Y. to Florida and westward," Wolle.* Europe. 



Family 5. OEDOGONIACEAE. 

 Fronds aquatic, in one European species terrestrial, consisting 



*C. amoena Wolle, 1887, p. 105, PI. XCI, figs. 18-23, with filaments cyl- 

 indrical, 7-12 AC diam., cells 2-3 diam. long, fructification by zoospores of 

 two sizes, can hardly be recognized from the description ; there is really 

 nothing to indicate that it is a Cylindrocapsa. 



