918 DR. LINDSAY ON WEST-GREENLAND LICHENS. 
The reaction of potash with the Greenland Cladonie is most capricious. Frequently 
it was lemon-yellow. Equally frequently no reaction was exhibited. Never was it of 
any significance, and still less of any use, in classification. 
As the result of his examination of the Cladonic in the Acharian and Florkean Herbaria, 
Coemans points out *, as I have elsewhere done t, how useless, and mischievous to 
science, is excessive elaboration in the nomenclature of varieties and forms. Acharius 
himself admits the impropriety of attaching names to trivial forms, when he says 
(*Synopsis, p. 258), * vix sub nominibus singularibus denotari merentur."  Coemans 
therefore proposes, as I have done, the abolition of a large number of names of varieties 
or forms—names that indicate only trivial and inconstant conditions of growth ! 
Of the Greenland Cladonie, the following are the only types that have good claims 
to the position of species :—1. C. rangiferina, 2. C. uncialis, 3. C. furcata, 4. C. gracilis, 
5. C. squamosa, 6. C. pyzidata, 7. C. cornucopioides. All the others are to be regarded 
as mere varieties, forms, or conditions, more or less of inconstant character, not unfre- 
quently referable to two or more species or types. To this category belong also the 
pseudo-species cespititia, cornuta, digitata, polydactyla, and many others. 
The genus Cladonia may be regarded as the equivalent or representative among 
lichens of the phænogamous genera Rubus, Hieracium, and Salie—with no very clearly 
isolated types, but with hosts of erosses or intermediates, having characters so change- 
able as to defy definition! 
Gen. 6. STEREOCAULON. 
1. S. tomentosum, Fr.—Egedesminde; Jakobshavn. Never in fruit. Frequently 
occurs in a subisidioid condition, muscicolous, or growing among moss, apparently 
young or rudimentary, as well as sterile, no podetia being developed. The thallus is 
very white, very irregularly granular or tuberculate, apt to be confounded with states 
of various Lecanore, e.g. tartarea and oculata. The pulvinuli forming this white isidioid 
crust are frequently large and sparsely scattered. Were a name necessary for such a 
mere condition of development, coralloidea would be most appropriate. With potash, 
the terminal white phyllocladia, or the young, rudimentary, coralloid thallus, give a 
greenish (lemon) yellow reaction, which may be vivid or very faint; or there is no 
reaction. There is great confusion in herbaria, as well as in systematic works, between 
tomentosum, alpinum, denudatum, and other so-called species. "Thus a specimen of 
alpinum from the Pyrenees, Nylander refers (in Kew Herbarium) to denudatum. It is 
unnecessary and a waste of time to endeavour to reconcile these differences in opinion 
between systematists, seeing that there appears no better ground for dividing the genus 
Stereocaulon into a number of species than what can be found to support similarly 
elaborate classification among the Cladonie. 
S. alpinum, in Spitzbergen, is the seat of the parasitic Biatorina stereocaulorum, Th. 
Fries (L. Arct. p. 188), which occurs on its phyllocladia also on the Alps of Eastern 
* « Cladoniæ Achariane :” Bulletin de l'Académie Royale de Belgique, ser. 2, t. xix; or translated by Leighton, 
in Ann. Nat. Hist. vol. xviii. 1866, p. 313 et seg. eee 
+ “The Arctic Cladoniæ,” Trans. Botanical Society of Edinb. vol. ix. 1867, p. 175. 
