206 REVIEWS—THE LICHEN-FLORA OF GREAT BRITAIN. 
The Lichen-Flora of Great Britain, Ireland, and the Channel Islands. By 
the Rev. W. A. Lricuron, B.A., &c. Third edition. Shrewsbury: For 
the Author. 1879. 
WE hail this book with pleasure as a valuable contribution to the Lichen 
literature of our country. It is now more than a quarter of a century 
since the Ray Society published a volume by the same author, “ British 
Species of Angiocarpous Lichens,” which was the first systematic attempt 
made to derive distinguishing specific characters from the spores, their 
form, size, and mode of septation. The present work being the result of 
the many years of subsequent close and careful application of the author 
to the study of Lichens may be accepted as the most complete, while it 
is the latest, British work on the subject. The branch of botany with 
which this deals is confessedly difficult, but the difficulty is much 
enhanced by the absence of useful handbooks like the present, and we 
look forward to a fresh impetus being given to the study in this country 
by its appearance. The Lichen-Flora of Great Britain, including the 
Channel Islands, comprises no less than 1,710 species, forms, and varieties. 
If we deduct fiom these the forms and varieties we have 1,133 species, 
which are distributed into 77 genera, and these again are arranged under 
22 tribes, the whole forming four families, viz.: Byrssace1, ConLEMACET, 
Myrianeracer, and Licnenacer. Three of the larger genera, Lecanora, 
Lecidea, and Verrucaria, comprise no less than 677 species, considerably 
more than one-half the whole Flora, but, by a very easy method based on 
the character of the spores, these genera are sub-divided in such a manner 
as very much to facilitate their study. The classification adopted is 
mainly that of Dr. W. Nylander, with such modifications as the author 
considered necessary, and we are glad to find that there is no great 
departure from that with which we are already familiar. A diagnosis of 
every species, the material on which it grows, its synonyms, references to 
plates when they exist, geographical distribution, as well as the distribu- 
tion in Britain, according to Mr. Hewett Watson’s well-known method, a 
specification of the exact habitats, with the names of those gentlemen on 
whose authority it is recorded, are given. The chemical reaction used so 
extensively by all leading Lichenologists is given in cases where it is ob- 
tained to assistin the determination of species. Some botanists smile at the 
adoption of this method of testing, as being chemistry and not botany, but 
we see little chance of its being abandoned so long as it serves to help 
with the other characters of a plant in the distinguishing of species. Mr, 
Leighton has wisely devoted a little more space in the introduction than 
was given in former editions to explain the method of applying the 
chemical tests, about which there should exist no uncertainty in the mind 
of the student, as serious errors may result from their misapplication. 
Another valuable addition is the microscopic measurements of the spores, 
taken from Mudd’s “ British Lichens,” the writings of Dr. Nylander and 
Thos. M. Fries, supplemented with the author’s own measurement. 
Those from the first-mentioned of these authors are the least reliable, 
and should in all cases be carefully tested by those of Nylander, Fries, 
and Leighton, which may be safely depended upon. A few points of 
much interest are touched upon briefly in the introduction, such as the 
morphology and physiology of Lichens, and the Schwendenerian theory of 
their parasitism on fungi, which we should have been pleased to have 
seen greatly extended. A list of authors cited, and published Exsiceati 
quoted, are given at the end, with a full glossary of terms and a copious 
index of species. W.P. 
