PYCNIDES OF CRUSTACEOUS LICHENS. 191 
cluding in them the many and various subgenera of modern continental systematists. 
This remark has more especial reference to Lecidea and Lecanora. Some of the fore- 
going genera, or some of their species, are not crustaceous ; but the character either of 
their apothecia or spermogones leads them to be classed with crustaceous, rather than 
with foliaceous, lichens. . Several genera or species have a subfoliaceous or subsquamulose 
thallus, e. y. the genus Endocarpon ; the Psoroid Lecidee—such as L. canescens, lurida, 
glauco-lepidea, decipiens ; and the Placodioid or Squamarioid Lecanore, such as leucolepis, 
callopisma, cervina. But Endocarpon is now uniformly classed with Verrucaria on ac- 
count of its angiocarpous apothecia; while the mere form of the thallus is insufficient 
to separate the subfoliaceous or subsquamulose Lecidee and Lecanore, unless in sub- 
genera or sections. The Caliciei are associated by systematists with the Spherophorei ; 
but their spermogones and pycnides are of the character of those of Verrucaria, while 
they are seated, moreover, on the horizontal crustaceous thallus. The genera herein- 
above enumerated may therefore be regarded as a natural group, so far as concerns their 
spermogones and pycnides. Considered as representing or constituting the lower lichens, 
they differ as a group in several important partieulars from the higher forms, e. g. in the 
much greater frequency of the occurrence of pyenides * in the former. 
While making the careful examinations necessary for the detection of spermogones and 
pyenides, I have met with several apparently new (that is, undescribed) Lichen-species or 
varieties. Several of these I described in my first memoir; while a few additional are 
now described, such as Lecanora Carollii, and L. cervina var. collematoides. 
The Preface or Introduction to the first memoir t applies equally, so far as it goes, to 
the present or second. But there are certain peculiarities of the lower lichens—as respects 
their spermogones and pycnides—when contrasted with the higher ; so that it is desirable, 
if not necessary, here to make the following additional general introductory or explanatory 
remarks. 
Perhaps the most important and novel of the incidental results of my researches is the 
ample demonstration they seem to me to afford of the phenomena or attributes to which 
I venture to give the names of 
Polymorphism and Plurality of Organs.—l use both these terms in reference to the 
variation-forms of spermogones and pyenides in the same species, and frequently in the 
same individual. But the distinction I draw between them is in the application of the 
former term (Polymorphism) to the variations of what are essentially the same organs or 
bodies, and the latter (Plurality of Organs) to what are markedly or presumably different 
conceptacles or corpuscles}. In the one case the variations are those simply of degree, 
in the latter there are differences that may be considered to be in kind. Polymorphism 
relates to the extreme variability of spermogones and pyenides, both in outward character 
and internal structure. It includes irregularities or peculiarities, exceptional or unusual 
conditions, relating, e. g. in— 
* Vide also paper on ** Polymorphism," p. 8 
t Including the Summary given in the Bain. Royal Society * Proceedings,’ vol iv. p. 174. 
t Some years ago I devoted a special Paper to the exposition of these phenomena: viz. that on * Polymorphism i in 
the Fructification of Lichens,” Quart. Journal of Microscopical Science, January, 1868. 
252 
