WITH NOTES ON OTHER SPECIES. 129 



oogonia, large, clavate-cylindric, on short branches of androgynous or diclinous origin, 

 sometimes even from the oogonial branch. Oospores single, globular, centric, 20 to 22,a 

 in diameter. 



Massachusetts — Amherst. Europe. 



The present species appeared in a single culture from moss and Algae (chiefly 

 Tolypothrix) from the mossy pool frequently mentioned, which had stood in a jar in 

 the laboratory for several months. It is readily distinguished by its smooth oogonia 

 from all other species except the smoothest forms oi Apli. scaber, from which it differs 

 in its large and numerous antheridia and larger oospores. The fertilization tubes are 

 plainly developed and the species seems in all respects to represent the most primi- 

 tive form of the genus. 



It is worthy of remark that, although the genus was described more than thirt}^ 

 years ago, no other species than the four then characterized have yet been recognized. 



Aphanomyces stellatus DeBary ('60). 



111.: DeBaiy, '60, PI. XIX, Figs. 1-13. 

 Sorokine, '76, PI. VII. 



Distinctly marked by its oogonia with large, blunt spines or warts, and its well- 

 developed antheridia, which seem to be present on every oogonium, combined 

 with its strictly saprophytic habit. DeBary states that in rare cases an oogonium 

 may contain two oospores, the only deviation from the one-spored condition known 

 to occur in the genus. 



This species has been studied by Sorokine ('76), as well as by its author, and is 

 probably common in Europe, and perhaps also in America, though I have not yet 

 met with it. It seems to be similar to the last species except in the spiny character 

 of its oogonia, a condition towards which, whatever its significance, there is a distinct 

 tendency in several groups of species in this family. 



Aphanomyces pliycoplnlus DeBary ('60). 



111.: DeBary, '60, PI. XX, Figs. 19-24. 



Although the zousporangia and sexual organs were not observed b} DeBary on 

 the same plant, there seems to be little doubt that this species is properh' placed 



