Pileus up to 8 x 5 mm when still closed, up to 15 mm when expanded, ellipsoid, cylindric-ellipsoid, often somewhat conical, white in very young stage, soon becoming somewhat grey or grey-brown at centre of pileus, expanding to campanulate or conical, then to convex or applanate, finally plano-concave with revolute margin, very thin. Veil in primordia smooth, mat, pure white, later greyish to grey-brown, covering entire pileus, soon radially splitting into hairy to fibrillose, often pointed and appressed or - especially at centre - recurved flocks. Lamellae, L = c. 16, l = 0-3, free, narrow, rather crowded, first white, soon grey-brown to blackish. Stipe 30-50 x 1-1.5 mm, whitish, somewhat tapering towards apex, up to 2 mm wide at clavate to slightly bulbous base, hollow, hairy flocculose but particularly densely at lowest part, becoming glabrous with age.
  Spores [80,3,2] 9.1-12.6 x 5.9-8.4 µm; Q = 1.40-1.85, av. Q = 1.50-1.75; av. L = 10.8-11.7, av. B = 6.4-7.4 µm, oblong or ovoid, more or less cylindric with rounded base and apex, dark red-brown, and central, 1-1.3 µm wide germ pore (difficult to observe). Basidia 14-36 x 7-10 µm, 2-spored, surrounded by 3-6 pseudoparaphyses. Pleurocystidia 40-80 x 20-40 µm, oblong, ellipsoid, ovoid or subutriform. Cheilocystidia 30-80 x 20-35 µm, (sub)globose or ellipsoid, a few subutriform. Pileipellis consisting of short, inflated elements, c. 20-100 x 4-20 µm. Veil made up of cylindrical or fusiform elements, usually inflated, incrusted and constricted at septa, 25-100 x 5-40 µm, the elements in part strongly swollen, fusiform, ellipsoid or even subglobose and up to 60(-70) µm thick. Clamp-connections present.

Habitat & distribution

  Solitary or (sub)fasciculate on dung of cow and horse. Very rare, only found twice in the Netherlands.

Remarks

  Coprinus bicornis can be recognized by the 2-spored basidia, the in part ellipsoid or subglobose elements in the veil and the habitat on dung.