158 
FETCH : 
thickness. The surface appears powdery, and when lightly 
rubbed the white upper layer comes off, leaving a pale brown 
surface. 
These patches occur in up-country jungles on the bark of 
living trees, the underlying tissues of which appear quite 
healthy. The species of tree has not been determined. A 
longitudinal section of a patch shows that the basal portion is 
composed of parenchymatous cells arranged in concentric 
layers round a central point. In some fresh specimens this 
structure continues almost to the periphery, but in the old 
herbarium specimens it is succeeded by a zone of partly dis- 
organized tissue. The whole of this stains yellow-brown with 
chlorzinc iodide. Here and there occurs a sohtary sclerenchy- 
matous cell, which stains pink with phloroglucin and hydro- 
chloric acid. 
The white external layer consists of a mass of amorphous 
granules. These dissolve in sulphuric acid without effer- 
vescence, and crystallize out in bundles of needle-shaped 
crystals on the slide. They ^are evidently composed of 
calcium oxalate. 
There is apparently no evidence of any Corticium in the 
structures in question. They appear to be a bark formation 
analogous to that of lenticels, with an external covering of 
calcium oxalate. 
113. — Irpex vellereHS B. &. Br. 
On the underside of decaying logs, in large sheets with a free 
dimidiate edge up to 5 cm. broad, spreading to, and surround- 
ing, grasses and shrubs in the neighbourhood. The upper 
surface of the free edge is dirty white, with concentric brownish 
zones, and strongly radially strigose. The species is remark- 
able, when fresh, for the strong differentiation of its substance 
into two distinct layers. The thickness, excluding the teeth, 
is 2 to 3 mm. ; the upper tw^o -thirds of this are white, soft, 
and spongy, composed of loosely interwoven hyphæ ; the 
lower third is also white, but forms a compact hrittle layer. 
The hyménium is white, becoming purplish or brownish ; 
sterile margin broad ; extreme edge tomentose, white 
becoming pale purple. Aculei irregular, compressed, often 
