T33 THE SPORES OF LICHENS. 
little smaller than the European, and measuring from .014 to 
.020. Sagedia cestrencis Tuck. is another example, though 
I am doubtful whether my specimens are different from S. 
carpinea Pers. As it occurs on the beech, the spores are 
fusiform, and measure from .034 to .038, while those on 
the hemlock, referred to the same species, are acicular and 
from .072 to .118. But perhaps the difference in form would 
justify making this a distinct species. Rinodina sophodes 
Mass. and Biatora rubella Fr. are two very variable species, 
but specimens referred to each vary in the former from .010 
to .025, and in the latter from .018 to .075. 
So in regard to the number of spores in the spore-case. 
The form of Rinodina sophodes in which the spore-cases 
contain twelve or more spores, can hardly be distinguished 
from that in which there are only eight, though Th. Fries 
makes it a separate species, under the name R. polyspora. I 
have found specimens of Buellia microcarpa D. C. which do 
not differ from the common form more than the two forms 
of R. sophodes, but in which there are from eight to sixteen 
spores in a spore-case ; and a parasitic lichen on the thallus 
of a Saxicoline Pertusaria which appears to differ from 
Buellia parasitica Flk., only in the spore-cases containing 
a large number of spores. These examples might be numer- 
ously increased, but they are perhaps sufficient to show that 
too much importance should not be attached to what Profes- 
sor Tuckerman calls “ mere gradal differences.” 
Nylander, the great French lichenist and the antagonist of 
the German-Italian school, does not seem to attach sufficient 
importance to the differences in spore characters. In his re- 
marks in his “Synopsis” on specific characters in lichens, he 
contents himself with a few indefinite observations in regard 
to them, and in his classification makes no generic distinc- 
tions based on form or color. Thus Rinodina is included 
under Lecanora, and Buellia under Lecidea. Indeed he 
seems to consider the spermatia as more important classi- 
ficatory organs than the spores. In his descriptions, however, 
