from tlie NortJiumberJand Coal-field. 225 



remarkable specimen the vesicles seem to be formed into a 

 connected congeries towards the margin. 



Another variety of these curious fungi has the outer bark 

 or cuticle rather thick ; and it seems to be composed of two or 

 three layers. Immediately within the innermost layer there 

 is a thin stratum of minute granules, which in some speci- 

 mens is much extended, and the granules enlarged. In the 

 former the quarter-inch object-glass is requisite to resolve 

 them ; in the latter an inch glass shows them very well. And, 

 what is rather peculiar, at certain points of the circumference 

 the bark or cuticle is folded inwards, the outer layer to a much 

 less extent than the inner ^ thus leaving a wide space between 

 the two. These inward foldings, of which there are three or 

 four, bulge considerably into the substance of the fungus, and 

 are somewhat reniform or ear-shaped. The stratum of gra- 

 nules follows the infoldings with the greatest regularity. 



There is still another variety, which differs considerably 

 from all the rest. This is without tubes, the whole substance 

 being composed of large polygonal cells having the appearance 

 of coarse cellular tissue, with here and there a dark, irregular, 

 spherical body. 



Such are the variations in the structure of these Coal- 

 measure fungi : they are, we have said, occasionally structure- 

 less or nearly so ; but this is rarely the case. We have six- 

 teen specimens that appear either homogeneous or almost so, 

 out of 126 sections, all the rest (110) exhibiting more or less 

 structure. This fact militates strongly against the idea we at 

 first entertained, that the tubular structm'e was a fungus para- 

 sitic in the bodies in which it is found. Were such the case, 

 these figures ought to be reversed : 16 bodies so affected might 

 be found in 126 ; but certainly we should never ex]3ect to 

 find out of that number 110 affected and 16 only free from the 

 parasite. 



The apparent entire homogeneity of some specimens, and 

 the apparent partial homogeneity of others, can be accounted 

 for as the result of fossilization. Fossil wood and other ve- 

 getable substances have frequently the structure either wholly 

 or partially obliterated by pressure. This is not uncommonly 

 the case with wood found in the Newsham Coal-shale ; and it 

 can scarcely be doubted that such is the case with the fungi in 

 question. We presume that the general substance of these 

 bodies is composed of cellular tissue (and, indeed, in one of the 

 varieties above mentioned we have seen that it is chiefly made 

 up of cellular tissue, and traces of such a structure have been 

 observed in one or two other instances), and that by pressure 

 this is almost universally obliterated. The ramifying tubes, 



