IOWA ACADEMY OF SCIENCES 
19 
conceive what he meant without seeing the specimens. 
This Wainio has done and has no doubt placed the forms 
where they belong. Indeed, it is apparent enough after 
Wainio has done the work, that Tuckerman’s diagnosis 
would apply to a form of Cladonia cariosa or to one of 
Cladonia siihcariosa quite as well as to Cladonia gracilis. 
Is it any wonder that we could never understand Cladonia 
gracilis while attempting to follow Tuckerman who placed 
forms of at least four species in one? 
In treating Cladonia gracilis, the writer considers him- 
self exceedingly fortunate in being able to see the speci- 
mens collected by Mr. G. K. Merrill, on Mount Washington, 
N. H., during the last summer. Indeed, but for the keen- 
eyed work of this collector in this best American collecting 
ground for the species, we could by no means give the 
presentation which appeared in a recent number of the 
Bryologist. 
It should be stated regarding Cladonia gracilis that the 
eastern forms are as a rule longer and more slender than 
the western. This appeared plainly enough in comparing 
the plants collected by Mr. Merrill with those found by the 
present writer in Minnesota and in Iowa. Also, Dr. L. H. 
Pam m el has collected a form of Cladonia gracilis elongata ' 
in Montana, which inclines to the shorter form, but still 
seems to be the variety. Also, Tuckerman states that the 
plants are paler in lower latitudes as in lower portions of 
Maine, Massachusetts and California. Our forms from 
Minnesota are paler than those of Merrill from New 
England, but it appears also that forms of Cladonia 
amaurocraea, quite elongated and cup-bearing, have fre- 
quently been placed under Cladonia gracilis. 
As indicated above, there is some real difficulty in dis- 
tinguishing between Cladonia gracilis and Cladonia verti- 
cillata. During the last summer. Dr. E. T. Harper collected 
and photographed lichens on Isle Royale, in Lake Superior, 
and the present writer is under obligations to him for the 
photographs from which the plate presented herewith was 
made. This plate shows forms of the two closely related 
