TIT 
and a better opportunity of examining the recent species than I have 
enjoyed. This might probably result in the reduction of some of 
the species herein mentioned. But a large accession may also be 
anticipated as the lichens of the world become better known. But 
little has as yet been done for the Arthonias of North America, and 
many additions may be expected to them, especially in the Southern 
and Western regions. 
The object of this publication will have been fully attained if it 
shall aid some more competent hand in making a complete and 
much to be desired study and elaboration of this difficult genus. To 
such I appeal for a lenient judgment of the errors and deficiencies 
which may be found in a perhaps presumptuous undertaking. 
The following arrangement is of course artificial, being designed 
to give some aid in the examination of species. Some might with 
equal propriety be referred to the series with colored, or to that with 
black apothecia. The color of the spores is mentioned only when 
they are brown, although typically all the Arthonia spores belong to 
the colored series. It has not been attempted to give all the syno¬ 
nyms of the older writers, and in general only the more recent exsic- 
cati known to the writer have been referred to. The spores of Ar¬ 
thonia are mostly 8 or 6-8 ; in a very few species 1-2. No Arthonias 
with polysporous thekes are known. As to the manner of develop¬ 
ment of the Spore, see Minks , Symbol#, p- xii. 
New' Bedford, Jan. 1890. 
f 
