42 College of Forestry 
in Maryland. In this case tivo groups of typical sporophores 
of Polyporus pargamenus had formed from the mycelium 
developing out of two insect tunnels about two inches apart 
in the bark. On adjacent portions of the bark were numer- 
ous typical sporophores of Polyporus abietinus. 
Probably one reason for the confusion of these two species 
may be that while the specimens collected from trunks of 
pine by the Franklin Expedition in arctic North America 
have generally been regarded as the type of our present-day 
Polyporus pargamenus, the plant that has gone under this 
name in the United States is practically always found 
on the wood of dicotyledonous trees. As Overholts (1915) 
states, this has led some authors to regard the original Poly- 
porus pargamenus as probably a synonym for P. abietinus. 
As stated earlier, some authors state that Polyporus par- 
gamenus and P. abietinus can be distinguished only on the 
basis of knowing whether they occur on coniferous or dicoty- 
ledonous hosts. Since the writer’s observations, as well as 
those of others, show that the determination as afforded by 
knowledge of the host cannot always be relied upon for the 
separation of these two species, it would seem advisable to 
consider them as biologic forms of the same species if they 
cannot be distinguished on the basis of their appearance and 
structure. To my mind, however, it is easily possible to 
distinguish, at least arbitrarily, between these two closely 
related plants by their appearance and structure alone. 
Overholts (1915) states that Polyporus pargamenus and 
Polyporus abietinus are very closely related and that they 
are connected by intermediate forms to such an extent that 
it is difficult to refer some collections to their proper species. 
However, he finds the usual form of the fructification to be 
distinct enough. It is his experience that P. abietinus is 
usually much the smaller, is frequently effused-reflexed with 
a narrow and often laterally continuous pileus, rarely more 
than two em. in length, and that the tubes often break up 
into lamelle-like plates —a condition which, so far as the 
writer’s knowledge extends, has never been observed in Poly- 
porus pargamenus. According to the same author that 
