172 AGARICUS. 



Pleurotus. villous base. Gills decurrent, somewhat crowded, narrow, rather 

 thick, simple. 



Exceedingly changeable in form, but most distinct from the rest, thin, for 

 the most part springing from an effused flaxy mycelium which is of the same 

 colour. 



On grassy open hillside. Penzance, 1869, &c. Aug.-Dec. 



Name mutilus, maimed. Perhaps from its variety of form. Fr. Monogr. 

 i. p. 247. Hym. Eur. p. 173. Icon. t. 88. /. 4. B. & Br. n. 1221, 1647. S. 

 Mycol. Scot. n. 212. C. Illust. PL 275. Omphalomyces mutilus Batt. t. ix. f. e. 



**** y e ft none j giH s deeply decurrent; pileus sessile, S*c. 



372. A. ostreatus Jacq. Pileus 7.5-12.5 cent. (3-5 in.) broad, 

 when young almost becoming black, soon becoming pale, fuscous- 

 cinereous, passing into yellow when old, fleshy, soft, conchate, 

 somewhat dimidiate, ascending, smooth, moist, even, but some- 

 times with the cuticle torn into squamules. Stem shortened or 

 obliterated, firm, elastic, ascending obliquely, thickening upwards, 

 white, strigoso-villous at the base. Gills decurrent, anastomosing 

 behind, somewhat distant, broad, white, sometimes turning light 

 yellow, and without glandules. 



For the most part caespitose, imbricated, very variable, sometimes almost 

 central. The pileus is at first convex and horizontal, then expanded and 

 ascending. In the anastomosing gills it agrees with A. corticatus and A.glan- 

 dulosus, and differs from all neighbouring species. There are numerous varie- 

 ties : flavo virens Brig. t. 44. f. 1-3, melanodon Brig. t. 45. f. 1-3. Inzenga t. 4. 

 f. 2, small, single, pileus black. There is another more remarkable form with 

 the stem distinct and the pileus horizontal. Fl. Dan. t. 891. Vivian, t. 42. 



On trees, especially laburnum. Frequent. Autumn-Spring. 



Berkeley notes having seen the species with glandular gills. He also de- 

 scribes the gills as serrated and umber at the edge. Badham describes the 

 gills as " standing out sharp and erect like the fine flutings of a column, wind- 

 ing down the stalk to different lengths, and those that reach the bottom form- 

 ing there a beautiful raised meshwork highly characteristic." Known as the 

 Oyster fungus, but this is from its shape, not its taste. Long celebrated for 

 its esculent qualities. Clus. Esc. gen. vi. It must be carefully distinguished 

 from A. euosmus which is unsafe. Remarkable for enduring cold. Spores 

 8x4 mk. W.G.S. Name ostrea, oyster. From its shape. Jacq. Austr. 

 t. 288. Fr. Monogr. i. p. 245. Hym. Eur. p. 173. Sverig. atl. Sv. t. 46. 

 Berk. Eng. Fl. v. p. 71. Out. p. 135. C. Hbk. n. 118. Illust. PL 195. S. 

 Mycol. Scot. n. 213. Sow. t. 241. Hussey ii. t. 19. Badh. i. t. 2. ii. t. 10. 

 Vittad. Mang. t. 4. Krombh. t. 41. Ventur. t. 17. Brig. t. 43. /. i, 2. A. 

 dimidiatus Bull. t. 508. 



373. A. euosmus Berk. Pileus 7.5 cent. (3 in.) broad, at first 

 white, invested with a light blue varnish, at length of a light 

 brown, depressed, shining and satiny when dry. Stems short or 

 obsolete, confluent. Gills very decurrent, rather broad, ventricose, 

 dingy white. 



