104 FRESH- WATER ALG^E OF THE UNITED STATES. 



SPHAEROPLEA ANNULINA, Ag. 



Green, yellowish, brick red or scarlet ; cells 8-10-20 times 

 as long as broad, with 20-30 chlorophylose rings in each 

 cell ; spores at length densely seriate, rarely disposed irreg- 

 ularly ; at first green, afterwards olive-brown and then red. 



Diameter veg. cells, 36-72 yw. 

 Diameter oospor., 17-36 /*, 

 Diameter spermat. , 8-9 ^ ; long. 

 Diameter zoosp., 11.5-16 A*; long. 



As far as my personal observations aid me, this genus has 

 no representative in the United States. In Europe it appears 

 frequent in quarries, pits and inundated fields. It is 

 reported from California but without certain knowledge 

 as to locality. The characters and figures are taken from 

 European works. 



Plate CXXIII, fig. 1, a filament with chlorophyl in rings ; 

 fig. 2, shows arrangement of mature (red) spores; fig. 3, a 

 frequent appearance of filament previous to development of 

 spermatozoids ; fig. 4, escaped spermatozoids, highly magni- 

 fied ; fig. 5, zoogouidia. 



Genus 13, CYLINDKOCAPSA, Beinsch. 



Filaments primarily attached ; later floating ; composed of a 

 single series of cells ; cells short, cylindrical, spherical or oblong, 

 chlorophyl green, containing numerous starch grains ; cell walls 

 colorless. Oogonia are developed in the vegetative cells, each 

 cell forming one spherical or ovate oogonium. Antheridia are 

 formed in small cells which appear in pairs in the same filament 

 with the oogonia and produce each two, somewhat elongated 

 spermatozoids, each furnished with two cilise, by means of which 

 they make their way to the oogonium and fertilize it, producing 

 an oospore clothed with a twofold membranous envelope ; these 

 oospores sometimes multiply by direct division, dividing into 

 four parts, each producing a young plant ; or they may divide 

 into two and these again into two, thus making four ; each of 

 these in turn producing four, thus developing sixteen young 

 plants. These processes were observed repeatedly in the months 

 of July and August. The same oospore may lie dormant 

 through the Winter and develop the following Spring. 



CYLINDROCAPSA GEMINELLA, Wolle. 



Vegetative cells ellipsoidal, more or less elongated as they 

 approach division ; normally they are about one half longer 



