After all, however, Ferns are most at home where there is a comparatively deep shade with abundance of moisture. Many species which will grow in somewhat dry situations attain a much finer development under happier conditions. Luckily many kinds of Ferns are still very common in the United Kingdom. Of course, in much-visited localities the ravages of the trippers have practically exterminated some interesting species in these particular districts. Naturally, one hardly expects to find the Royal Fern flourishing to any extent in the popular holiday haunts—none the less, there are still any number of places where this noble plant “grows like a weed.” The wise man does not talk about such things to his friends. Many of our most beautiful Ferns are saved even in much-frequented places on account of the fact that they grow out of reach. No doubt the graceful Trichomanes of South Ireland would long ago have been stamped out in the Killarney district, were it not for the fact that it often grows in situations which it is almost impossible for anyone to reach. As far as number is concerned, the living Club Mosses represent a comparatively insignificant group when compared with the Ferns. In all the world there are probably not more than five or six hundred species. These are very widely distributed, and there is hardly any part which cannot offer at least a few species. We have five species of Lycopodium in the United Kingdom. All are rather local, though often enough they occur in great abundance in special localities. Only one (_Lycopodium inundatum_) ever occurs in lowland districts; all the rest must be looked for on highland moors. A few exotic Lycopodiums grow to a fair size, though this is largely due to the fact that their creeping stems straggle along the ground for a considerable distance. The Selaginellas are a much more important group as far as the world generally is concerned. There are certainly as many as four or five hundred species, and some of these assume almost a shrubby habit. A species from Borneo (_S. grandis_) is said to attain the height of two feet. In the United Kingdom we have but a single species of Selaginella—_S. spinosa_, an insignificant little plant. Many exotic kinds are frequently grown in greenhouses, so that a variety of species is within the reach of everybody.