362 AQUATIC PHYCOMYCETES 



structure was borne in the larger, upper, part of a septate toplike body, 

 the lower part of which was empty. 



Whereas Zopf observed the fungus to gain entrance into the host only 

 at the unsilicified line of fusion of the valves, Scherffel has noted that 

 germinating zoospores may in some cases bore through the valve at any 

 point. 



PODOCHYTRIUM LANCEOLATUM Sparrow 



Trans. Brit. Mycol. Soc, 18: 216. 1933; J. Linn. Soc. London (Bot.), 50: 450, 



fig. 4c-f. 1936 



(Fig. 21 K, p. 360) 



Sporangium sessile, lanceolate or somewhat fusiform, often slightly 

 tilted, with a small apical papilla, wall smooth, colorless, 20-25 ;x high 

 by 8-10 u, in diameter, tapering at each end to 3-4 jx, resting upon a 

 sterile cuplike or occasionally knoblike base 4-5 \l in diameter; rhizoidal 

 system consisting of a few sparsely branched rhizoids arising from the 

 tip of a prolonged needle-like penetration tube; zoospores spherical, 

 3-4 [x in diameter, with a single refractive eccentric globule and a long 

 flagellum, emerging through a small apical pore formed upon the deli- 

 quescence of a papilla; resting spore not observed. 



On Melosira varians, Great Britain. 



Differing from Podochytrium clavatum in the shape and greater length 

 of its sporangium, smaller apical pore, and complete lack of a stalk on 

 the sterile part. The species resembles to a certain degree the immature 

 plant of P. clavatum figured by Zopf (1888: pi. 20, fig. 25e). 



Podochytrium cornutum Sparrow 



Trans. Brit. Mycol. Soc, 34: 172. fig. 1. 1951 



(Fig. 11 H, p. 110) 



Sporangium smooth-walled, narrowly clavate, 33-58 \x (av. 45 u.) long 

 by 10-13 fx in broadest distal portion, tapering to 3-4 jx in diameter at 

 the base of the narrow, 10 jx long concomitant sterile part; the whole 

 resting upon the rounded body, 3-4 ;x in diameter, of the encysted 

 zoospore; rhizoidal system coarse, much branched, usually conspic- 



