We may add to these three or four other species, in which the stem is lateral, and sometimes nearly obsolete. The largest and most common is the oyster mushroom (_Agaricus ostreatus_, Jacq.[K]), so universally eaten, that it is included in almost every list and book on edible fungi; it is the most common species in Transylvania, tons of it sometimes appearing in the markets. It does not possess that delicate flavour which is found in many species, and although extolled by some beyond its merits, it is nevertheless perfectly wholesome, and, when young and carefully cooked, not to be despised. It must not be confounded with a very similar species (_Agaricus euosmus_, B.), with rosy spores, which is unpleasant. _Agaricus tessellatus_, Bull, _Agaricus pometi_, Fr., _Agaricus glandulosus_, Bull, are all allies of the foregoing, and recorded as edible in the United States, although not one of the three has hitherto been recorded as occurring in Great Britain. To these may also be added the following:--_Agaricus salignus_,[L] Fr., which is rare in England, but not uncommon abroad and in the United States. In Austria it is commonly eaten. _Agaricus ulmarius_,[M] Bull, is common on elm trunks, not only in Britain but also in North America, and is by some preferred to the oyster mushroom. An allied species, _Agaricus fossulatus_, Cooke,[N] is found on the Cabul Hills, where it is collected, dried, and forms an article of commerce with the plains. Another, but smaller species, is dried in the air on strings passed through a hole in the short stem (_Agaricus subocreatus_, Cooke), and sent, it is believed, from China to Singapore. The smallest species with which we have any acquaintance, that is edible, is the "nail fungus" (_Agaricus esculentus_,[O] Jacq.), scarcely exceeding one inch in diameter of the pileus, with a thin rooting stem. The taste in British specimens when raw is bitter and unpleasant, but it is clearly eaten in Austria, as its name testifies, and elsewhere in Europe. It is found in fir plantations in the spring, at which season it is collected from the fir woods around and sent to Vienna, where it is only used for flavouring sauces under the name of "Nagelschwämme."