1034 AQUATIC PHYCOMYCETES 



Antheridium diclinous, clavate with tapering apex; 

 zoospores 7.5 by 4 jjl ; oospore 13-20 by 15-21 y 



(Fig. 86 J) P- marinum Sparrow, p. 26m 



Antheridium monoclinous, beaked ; zoospores 6-9 y. 

 long; oospore 16-24 y in diameter 



P. maritimum Hohnk x 

 Oospore aplerotic (i. e., not filling oogonium) 

 Oospore wall noticeably thickened (inspissate) 

 Antheridium diclinous, never monoclinous 



Antheridial cells one or rarely two to an oogo- 

 nium, each borne on a separate antheridial 

 branch, inflated-clavate, not greatly curved, 

 applied narrowly to oogonium; zoospores 

 6-8 y by 3-4 y\ oogonia 14-27 y (mostly 15- 

 24.2 y) in diameter; oospore 1 1—21.5 jx (most- 

 ly 12-21 y)\ in fresh- water green algae (Fig. 



86 E) P. gracile Schenk, p. 31m 



Antheridial cells one to four to an oogonium, 

 arising as lateral prolongations of a single 

 antheridial branch, crooknecked, clavate; 

 hyphae forming numerous appressoria; zoo- 

 spores 10 by 5.4-9 y; oogonia 10-25.2 y (av. 

 17.5 y) in diameter; oospore 7.2-21.6 y. (av. 

 14.4 (j.), wall 2-2.5 y thick; in fresh-water 

 green algae (Fig. 84 A-B; Fig. 86 C, I, K) 



P. adhaerens Sparrow, p. 34m 

 Antheridium usually monoclinous, occasionally di- 

 clinous, one to five, arising separately, often ses- 

 sile when monoclinous, when diclinous usually 

 arising near the oogonium, arching, antheridial 

 cell crooknecked, inflated, breviform, 6-16 by 

 5-8 y, the apex making broad contact with the 

 oogonium; oogonium usually terminal, occa- 

 sionally intercalary, spherical or subspherical, 

 occasionally with a single papilla, the delimiting 

 cross wall sometimes inserted beyond the 

 oogonial contour, 12-33 y (av. 20.7 y) in 

 diameter; oospore with moderately thickened 

 wall (.8-1.4 y), nearly filling oogonium, 1 1-27 y 

 (av. 17.6 y) in diameter; sporangia sometimes 

 including slightly swollen elements; zoospores 



1 Kieler Meeresforsch., 111(2): 347, fig. 4. 1939. 



