248 FUNGUS-FLOEA. 



Var. undulatus. Fr., broadly expanded, marginate, pale 

 bay-brown. 



** Pileus white, pale ochraceous, yellowish, &c. 



Polyporus betulinus. Fr. 



Pileus thick, corky, elastic, hoof-shaped, obliquely um- 

 bonate behind, and forming the point of attachment, margin 

 obtuse, incurved, sterile below, pileus covered with a thin 

 crust that eventually breaks away, whitish, zoneless, glabrous; 

 pores up to |- in. deep, minute, unequal, whitish; spores 

 white. 



Polyporus betulinus, Fries, Syst. Myc. i. p. 358 ; Greville, 

 Scot. Cr. Fl., t. 246. 



On trunks of birch, &c. Distinguished by the white, corky, 

 very fleshy pileus having the margin incurved, 3-8 in. across, 

 flesh white, soft, very thick behind, horizontally attached by 

 the posterior, oblique umbo. Pores very minute, about 

 1 mm. 



Pileus 46 in. across, smooth, pale reddish-brown when 

 mature, often mottled, roundish or sometimes reniform. 

 Flesh white, very thick ; pores white or tinged with brown, 

 narrow, the orifices toothed, separable from the pileus when 

 fresh, but really concrete with it. (Grev.) 



Taste and smell acid. The epidermis is very thin and 

 delicate, and easily peels off; when dry the whole plant is 

 very light ; its texture between coriaceous and corky. 

 (Berk.) 



Polyporus borealis. Fr. 



Horizontal, subspathulate or reniform, either attenuated 

 behind into a short, more or less distinct stem, or thick and 

 sessile, 23 in. across, whitish then dingy yellow, spongy 

 then corky, compact, hairy, flesh thick, composed of parallel 

 fibres, whitish ; tubes 2-3 lines long, pores unequal, flexuous, 

 dissepiments thin, torn, white ; spores colourless, subglobose, 

 4 fj. diameter. 



Polyporus borealis, Fries, Syst. Myc. i. p. 366 ; Stev., Brit. 

 Fung., p. 202. 



On stumps and trunks of pine, &c. Pileus often radiato- 

 rugose, rigid and more or less incurved when dry. When a 

 stem is present the tubes are more or less decurrent. 



