PYCNIDES OF CRUSTACEOUS LICHENS. 197 
investigations; and illustrations may be found under the following species in the present 
memoir :— 
Lecanora subfusca, no. 17. Lecidea contigua, nos. 3, 6. 
polytropa, nos. 3, 4. parasema, nos. 9, 11, 12. 
Carrollii. geographica. 
—— hematomma. Opegrapha vulgata, no. 8. 
sophodes, no. 3. atra, no. 2, 
—— cerina, nos. 2, 3. saxatilis. 
leucolepis. Graphis anguina. 
Pertusaria ceuthocarpa. Arthonia astroidea, no. 1. 
pustulata. cinereo-pruinosa. 
Lecidea aibo-atra, no. 1. impolita, no. 4 
— — myriocarpa, no. 1. —— ilicina. 
—— quernea, nos. 1, 2. Stigmatidium crassum, no. 3. © 
—— uliginosa. Verrucaria epidermidis, nos. 1, 2. 
— — abietina, no. 12. 
gemmata, no. 4. 
—— atro-grisea, no. 3. 
biformis, no. 2. 
—— rosella. 
Leightonii, no. 1. - 
—— anomala, no. 1. Calicium tigillare. 
synothea, no. 2. 
eusporum. 
—— minuta, no. 1. 
pallidum. 
When we consider the utter confusion of synonymy in systematic works; the excessive 
redundancy of names of species and varieties; the diversity of opinion that exists between 
different lichenists as to what are species and varieties; the incessant changes of nomen- 
clature and classification in the works even of the same author; the difficulty of deter- 
mining species by mere book-characters or definitions instead of from specimens authen- 
tically named by the discoverers and describers of so-called ** new species;" the unsatis- 
factory nature of the said ** characters ” or definitions; the too frequent establishment of 
species or genera on single specimens; the impossibility of any individual lichenist 
making himself acquainted with all the contributions to lichenology that are constantly 
being made in Europe alone; the superficiality of the examination that is usually made 
by systematists, whose aim is merely to determine the name and place in classification of 
a given lichen, not to ascertain its whole natural history,—it cannot excite surprise that 
errors in determination should be common even with the most distinguished systematists ! 
Thus I have found errors of nomenclature repeatedly in the Kew Herbarium, the spe- 
cimens in which have had the advantage of being examined and named by the most 
eminent lichenists of the present day as well as of by-gone times. I have also had occa- 
sion to find, in the careful examination of every organism that occurs on hand specimens 
in that and other herbaria, that the best-known systematists have contented themselves 
with noting the apothecia and sporidia of the most prominent, or, to them, the most 
interesting, lichen on the said specimens, and have thereby failed to detect organisms of 
much greater importance and rarity, whose discovery, however, required a much greater 
sacrifice of time and patience. 
I need scarcely perhaps add, then, that I claim no greater freedom from error than 
VOL. XXVIII. | | 2r 
