22 
IOWA ACADEMY OF SCIENCES. 
that C. H. Persoon had in the opening year of the period 
(1810), in a work published in Europe, given a list of 42 
lichens from San Domingo arid the North American conti- 
nent. Finally taking up Tuckerman’s beginnings, which 
belong to this period, we find that he published in five 
papers (1889-1845) on the lichens of New England, lists 
aggregating upward of 200 species and varieties. Also in 
1845 appeared “An Enumeration of North American 
Lichenes with a preliminary view to the Structure and 
General History of these Plants and of the Friesian Sys- 
tem,” in which are enumerated 288 North American 
lichens. Of these only three are new, and this indicates 
that Tuckerman had not yet begun any extensive species- 
making. A list of 58 species given in T. G. Lea’s work on 
the plants near Cincinnati appeared in 1846, this complet- 
ing our survey of Tuckerman’s works of the period. 
Thus the period begins with a few more than 100 known 
North American lichens and closes with scarcely 250. 
With the exception of the few species known from the 
western coast and mountains, the work was mostly con- 
fined to the New England states, New York, Pennsylvania 
and Ohio. American papers appear as already noted, and 
some of them would appear quite noteworthy even at the 
present time. The whole number of titles for the period 
is 89, and it is not thought necessary to name the minor 
ones. 
THE TUCKERMANIAN PERIOD ( 1847-1888.) 
In taking up this period we pass from comparatively 
small things to what Henry Willey fittingly called “the 
golden age of American lichenology ”. During this time,, 
everything in American Lichenology was colored by the 
views of the one man, Tuckerman. However, in dealing 
with the period, it seems expedient to consider the work of 
others first and close with that of the man who stands pre- 
eminent among American lichenists. Among Europeans 
who have worked on our lichens during the period, we can 
give space only to Th. M. Fries and W. Nylander. Fries 
in his “Lichens Arctio Europae, Gronlandicaeque ”, pub- 
