JULY. 
25] 
colour^ above, from dull white to bright polished brown, like 
mahogany. They grow on many trees^ but seem chiefly to 
affect the birch : they are also very frequently found on the 
underside of upturned roots. From the elevated ridges on 
the surface, forming parts of concentric circles parallel with 
the edge^ it would appear that they grow not by gra- 
dual increase of the whole^ but by additions to the outer 
margin. Let us examine the structure of one of them^ 
which we shall find very curious. The upper part is of a 
tough leathery consistence, often becoming hard and woody ; 
the under part consists of a congeries of long capillary tubeS;, 
parallel with and close to each other, fixed on the under sur- 
face of the pileus or coverings and proceeding downwards at 
right angles to it. These tubes, though minute, are so 
straight, that if you cut off a piece of this part, and hold 
it up towards the light, slowly turning it, the light will sud- 
denly flash through them, when the orifices come opposite the 
eye, as through a spy-glass. This mass of tubes is elastic, 
and capable of taking up and holding a large quantity of 
water, like a sponge. This Boletus constitutes the food of 
some beetles ; if we examine more, we may probably find 
some. 
C. — Here are some ; they are monstrously ugly ; they 
are nearly square, of a dark earthy brown colour, and 
covered with rough, irregular prominences and depressions. 
Some of them have two projecting incurved horns on the 
thorax ; others have only slight prominences in their place. 
F, — From their roughness, colour, shape, and sluggish 
motion, I call them Toad Beetles ( Bolitophagus Cristatus ) : 
when molested, they draw in the antennse and legs, and lie 
as if dead ; and certainly in that position it would require 
an experienced eye to tell that they were living creatures at 
all. 
C. — Here are some large hollows in the porous part of 
