IOWA ACADEMY OF SCIENCES. 
29 
view, and no doubt botanists generally will be surprised at 
the statement that more than half of the known refer- 
ences to literature containing some reference to North 
American lichens belongs to the present short period of 
sixteen years. True the older titles are more difficult to 
find, but doubtless my present bibliography will not be 
very greatly increased. No recent American worker has 
accomplished so much as did Tuckerman in his long life; 
but the number of workers has increased, while the quan- 
tity and quality of work done by several of them is surely 
praiseworthy. 
In considering the workers of this period, I shall again 
take up first the labors of Europeans who have aided, and 
then the American workers. Among the former may be 
mentioned first J. Muller, whose work on our lichens 
began as far back as 1877, whose titles dealing wholly or in 
part with North American species number no less than 24, 
and whose North American new species number approxi- 
mately 125. Of these about 90 were described in the pres- 
ent period and add to our flora as known by Tuckerman. 
Next to Nylander, Muller is the European who has done 
most for American lichenology. E. Stizenberger had 
noticed some of our lichens, beginning as far back as 1861,. 
but so far as I am able to ascertain, his only papers dealing 
wholly with our lichen flora are two, written in 1895. In 
1890 he began examining the collections of H. E. Hasse, of 
California, and described quite a number of new species 
which have been published in papers by Hasse. Edward 
Wainio, of Helsingfors, has considered our Cladonias in his 
exhaustive “Monographia Cladoniarum Universalis” 1887- 
1898, and American students who would work on the genus 
must learn how to use his volumes. Dr. Wainio has in the 
last few years examined considerably more than 200 of my 
specimens of American Cladonias and a considerable 
amount of European material on which I have asked his 
aid. These specimens of the genus are very valuable, 
especially when it is stated that in all probability fully 
one-fourth of all American determinations of Cladonias 
would not endure Dr. Wainio’s critical examination. That 
