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specific appellation? Of variety rsl/iiobola, \Nh\uh., of Verrucaria m.nr- gacea, Wlilub. (p. 416), " It is often difficult to separate this variety from the type." Tlien why make an arbitrary division ? LeciJea sub- nigrata, Nyl. (p. 316), " vix separanda a L. deni.fjrota, says Nylander himself, who nevertheless creates the separate species. Lecidea circaiii- pullens, Nyl. is "vix nisi varietas L. bacciUifcr/B (p. 336). L. spo- dodes, Nyl. (p. 261), is "closely allied to L. deulgrata, Fr., and proljably a subspecies, though externally distinct." L. houinlolropa, Nyl. (p. 337) is " near to L. urceolatn, Ach. Doubtful if not bolh referable to Melas- pUeay Var. Jlavens, Nyl. of L. parasema, Ach. (p. 270), " Latet sub elodochroma, Ach. (ex lib. Ach.) a quti etiam parum diversa." Then wliy cumber an already complex Lichen-flora with unnecessary names and species? What necessity is there for, or what advantage in, naming and giving separate rank to such forms, conditions, or states, of species as var. terrestrls, Nyl. of Lecanora varia, or form cinerascens, Nyl., of L. badia ? This is a kind and degree of elaboration that is simply mis- chievous. It would seem, moreover, that, in not a few cases, species are based on a single imperfect specimen. This is the case apparently, for instance, with Pertmaria sublactea, Leight. (p. 24.5), of which it is noted that the spores are " unknown :" nor were they " seen " in the case of P.faginea, L. (p. 242).
In describing the " extensive portions of our country still unexplored as to Lichens," Mr. Leighton is in error in including " The whole of the north and north-western counties of Scotland, including the Hebrides, Ork- ney, and Shetland Isles." For so long ago as 1841, the Hebrides were botanically " explored " by Professors Balfour, of Edinburgh, and Babing- ton, of Cambridge, whose " Catalogue of the plants gathered in the islands of North Uist, Harris and Lewis," — including Lichens, — appeared in the 'Transactions of the Botanical Society of Edinburgh,' in 1844 ; while, so lately as 1866 and 1869, the Lichen-flora of Caithness, Sutherland and Inverness-shires, of Orkney, Sliethmd, and the Hebrides was the subject of special investigation by Dr. Lindsay. Large collections were made, and a list of some of the commoner species has already been published. Indeed in Mr. Leighton's own work he gives a number of localities in 'Lewis' (the Hebrides), 'Orkney'; 'Hebrides'; ' Coygach, Sutherlandshire ' ; 'northern parts of Scotland'; 'Long Island' (= the Lews or Lewis, Hebrides) ; ' Inchnadanf, Sutherland' ; ' Glen Ach-na-Sliilloch, Ross-shire' ; ' Loch Carron' (Ross-shire) ; ' Orkney Islaiuls' ; ' Brough Head in island of Stronsa, Orkneys' ; and ' Lerwick, in Shetland.' There can be no doubt, however, that for those Lichenists, whose ambition is to collect specimens, in the hope of Nylander, or other Continental nomenclator, discovering novelties or rarities among tiieir gatherings, there is still ample scope in the British islands, even in the districts that have been the most fre- quently and thorouglily " explored." But collectors are so much more numerous than biologists that we would counsel the student, instead of hunting for " new species," to devote his attention to those that have been already discovered, making himself master, not only of their na,ines and their specific duignoscs, but of all their characters, including their various uses. Such has been the activity of collectors and name-givers of late years, even since the issue of Crombie's 'Emimeratio' last year, that we can well afford to pause in our efforts to add to the number of the British Lichens, and cultivate a more thorough accjuaintauce with the pre- sent, only too numerous, meuibcrs of our Lichcn-llura.
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