300 LICHENS OF NOVA SCOTIA—MACKAY. 
appears to be a compound plant consisting of a parasitic fungus 
infesting, enveloping and modifying an algoid host. The fungus 
is the dominant element, the alga is the omnipresent gonidial 
layer of the older lichenologists. 
The reproductive system of the lichen is essentially fungoid 
ascomycetous group. The gonidia, on the other hand, have in 
many cases been shown to be a species of algve ; analytically, by 
freeing them from the investing fungi, when they develop into 
well known forms of algz ; synthetically, by sowing the spores 
of a lichen ; fungus on an appropriate species of algz; when a 
genuine lichen-thallus is produced. 
According to Schwendener, Peltigera, Pannaria, Leptogium 
and Collema are ascomycetous fungi parasitic on species of the 
Nostocacee ; Graphis and Verrucaria on Chroolepide ; Uonea, 
Evernia, Physcia and Cladonia on a species of Palmellacee. 
Lichens are found everywhere, and they can be preserved in 
the Herbarium with the least possible trouble. These facts 
should be a great stimulus to collectors. Many of them can also 
be easily determined with nothing more than the assistance of 
an ordinary lens ; although among the crustaceous and pustular 
species in particular, high powers are required to make out the 
characters of the reproductive organs upon which the classifica- 
tion is based. 
In the following pages, I give, at the request of our honored 
President, simply, a list of species with the localities in which 
they have been observed. It will be seen that my work in this 
department has been nearly exclusively, as yet, confined to west- 
ern Pictou. There are two or three doubtful species included 
and so marked, several others are withheld. 
Lichens of Pictou, et al., Nova Scotia. (Provisional list, ar- 
ranged according to Tuckerman’s Genera Lichenwm.) 
TRIB. I.—PARMELIACEI (fr., Eschw.) Tuck. 
Fam. 1.—USNEEI, F7. : 
Gen. .—Ramatina, Ach. DeNot. 
1. R&R. calicaris, Fr. Common on trees, old fences, &e., Pictou. 
Also, var. fastigiata, Fr. and var. farinacea, F. 
