736 AQUATIC PHYCOMYCETES 



ellipsoidal or oval-oblong, golden-brown, smooth-walled, 17-27 \x long 

 by 13-25 u. in diameter, germinating in situ. 



On submerged twigs, Thaxter (F.) (be. cit.), R. M. Johns (comm.) 

 (North Carolina), Benjamin (comm.) (Massachusetts), United 

 States; Thomas [PerroU] (1939: 124, fig. 1), twigs of Quercm 

 robur, Perrott (1955: 258, pi. 9 and fig. 3), Great Britain. 



R. M. Johns observed the true zoosporangia of this species and 

 says that they are narrowly cylindrical. The zoospores are posteriorly 

 uniflagellate not biflagellate (see Sparrow, 1943: 467). 



MONOBLEPHARIS FASCICULATA Var. MAGNA PerrOtt 



Trans. Brit. Mycol. Soc, 38: 260, fig. 4, 1955 



"Mycelium well developed, consisting of straight, rigid, cylindrical, 

 vacuolated hyphae, which are often pale brown, especially in the basal 

 portions, and hyaline near the tips; rarely branched, except near the 

 tip, 1-2 mm. long by 7-12.5 \x in diameter (average 7-10.5 \x); attached 

 to the substratum by branching rhizoids. 



"Oogonia arranged singly or in fascicles at the tips of hyphae, 

 cylindrical, contain a single oosphere, and open by a tube termed the 

 'neck' which is usually shorter than the antheridium and curved toward 

 it. Occasionally this tube is as long as the antheridium. Oogonia vary 

 in length from 32 to 54 jj. (majority 39-50 u.) ; diameter 21-36 \x (majority 

 25 n). 



"Antheridia long, cylindrical, and tapering at the tip, rarely sub- 

 conical, usually straight, but occasionally slightly curved towards the 

 neck of the oogonium; length 14-29 \x (majority 21-25 u,); diameter 

 5-1 1 \x (majority 7-9 \x tapering to 6-7 \l); always present, borne on the 

 oogonium (epigynous) to one side of the neck, which they always exceed 

 in length. Antherozooids 4-5 [J. in diameter, amoeboid and uniciliate; 

 usually 6 or 7 in each antheridium. Protandry is well marked. 



"Each oogonium contains a single oospore which matures and ger- 

 minates in situ (endogenous). Oospores pale brown in colour, walls 

 smooth, spherical, widely ellipsoid and cylindrical; length 24-36 u. 

 (majority 28-32 u,), diameter 17-29 [i (majority 23 fj.)" (Perrott, be. cit.). 



On submerged twigs of Quercus robur, Great Britain. 



