or kick from our path, because they appear to be only rotten sticks, withered grass, and decaying leaves. All this may appear as the dream of an enthusiast, or the ravings of one on whom the moon has shone too often. When Columbus spoke of a new world beyond the seas, which he longed to seek and explore, some believed him duped, and others called him mad. We write of no chimerical El Dorado, we speak of no undiscovered world, and yet we seem to allude to wonders still unknown, because so few have had the courage to venture upon the journey for themselves. In sober earnestness, however, let us commend this pursuit to all who possess a microscope and leisure to use it. It may be for a time the “pursuit of knowledge under difficulties,” on account of the condition of our literature on this special subject; but many workers will produce more readers, and good books will come when there are more to purchase and appreciate. It is not improbable that in more cases than have come under our own observation, microscopists wearied of diatoms and allied forms, or deeming themselves in possession of all that is novel or interesting in this direction, are seeking for a new field of labour, and a new subject to kindle up a new enthusiasm. To these we have advised, and to any more such we continue to advise, that fungi should have a fair trial. If variety is desired, here they will have at least 2,000 species for a knowledge of which the microscope is essential. If they thirst for discovery, let them be assured that here also the earnest worker is sure to meet with such a reward. Or if they would acquaint themselves with the manifestations of Divine power as developed in the most minute of created things, let them follow such observers as Tulasne and De Bary, and seek the “why and the wherefore” of the phenomena of mycetal life. If there should still be any hesitation whether there is in this pursuit sufficient of the element of variety, for those who do not desire to pursue the subject into its deepest scientific recesses, to render it available for them, let them go to a good public library, such as that of the British Museum, and inquire for the large illustrated work by Corda, entitled “Icones Fungorum,” or the more recent volumes by Tulasne (Selecta Fungorum Carpologia), and examine the figures of microscopic fungi in either of those works, and decide for themselves. ------------------------------------------------------------------------ APPENDIX A. ---------- CLASSIFICATION & DESCRIPTIONS OF FUNGI CONTAINED IN THIS VOLUME. ------- =ÆCIDIACEI=. Peridium elongated— separating in threads _Rœstelia_. rupturing irregularly _Peridermium_. Peridium abbreviated, or _Æcidium_. semi-immersed