[Illustration: Fig. 41. (1) _Agaricus orcella_ and (2) _Agaricus prunulus_ (Plum Mushroom). Woody places, in autumn; colour, snow-white, with pale rose gills; diameter, 2 to 4 inches.] _Agaricus prunulus_ (Plum Mushroom). _Pileus_ fleshy, compact, at first convex, then expanded, becoming depressed in the centre, irregularly waved, and slightly pruinose; from two to five inches broad; surface dry, soft, white, or sometimes grey. The flesh thick, white, and unchangeable. _Gills_ crowded, deeply decurrent, at first white, then a pale dull flesh-colour, or yellowish brown. Spores pale brown. _Stem_ white, solid, firm, slightly ventricose, an inch or more long, and half an inch thick; naked, often striate, and villose at the base; often eccentric. _Odour_ like that of new meal, but usually too strong to be agreeable. There has been considerable confusion, writes Dr. Bull, between the two Agarics _orcella_ and _prunulus_; some thinking that we have only _orcella_ in England (_Dr. Badham_); and others only _prunulus_ (the _Rev. M. J. Berkeley_), and others again that they are both the same fungus, differing only in size. Dr. Badham and some others again confuse _prunulus_ with _gambosus_, the fungus of early spring, and this has arisen from the French term _mousseron_ being often applied to both these funguses; but they are so essentially different as not to be liable in any way to be mistaken for each other. _Agaricus orcella_ and _A. prunulus_ are both placed on the same page in the illustration, so that their close alliance may be seen at a glance. Fries treats them as separate funguses, “in deference to ancient authority, since their differences are chiefly in degree.” These differences are, nevertheless, so well marked, that they are kept separate here. _Orcella_ is a smaller and more delicate fungus than _prunulus_. It is thinner and less fleshy, more undulated in its borders, and has a lighter and more agreeable odour. _Orcella_ grows in more open glades than _prunulus_; it is usually much whiter in colour, sometimes in high situations white and glazed as an egg-shell, or even pottery. _Orcella_ grows more solitary than _prunulus_, in light, scattered groups, showing an inclination for the neighbourhood of oak-trees, and where it does grow it may be found year after year in the same place, but seldom more than two or three in a spot. Last year, 1869, when _orcella_ was pretty plentiful, _prunulus_ was not to be found in the situations where it grows usually most abundantly. _Prunulus_ is the reverse of all this. It prefers more shaded places, is larger, more fleshy, and with a strong odour rather heavy and overpowering. It grows in greater quantities together, and not unfrequently in crowded rings from four to six feet in diameter.