238 NORTH AMERICAN FLORA [VoLUME 9 
Pileus thin, soft, coriaceous, sessile, suborbicular to flabelliform, convex to depressed, 
1.5-4 cm. broad; surface whitish-villose to hirsute, at times scurfy-incrusted and subglabrous, 
white to dull-ochraceous or umbrinous, margin radiate-sulcate, subentire to lobed, incised, or 
multifid; lamellae radiating, narrow, inserted, bifid, the edges revolute, villose, gray to purplish- 
brown: spores cylindric, smooth, hyaline, 6-7 X2-2.5 pu. 
TYPE LOCALITY: Sweden. 
Hapitat: Dead wood. 
DisTRIBUTION: Cosmopolitan. 
Innustrations: Atk, Stud. Am. Fungi f. 130; Sow. Engl. Fungi 1. 183; Jour. Bot. 30: pl. 322, 
f. 13, 14; Batsch, Elench. Fung. f. 126; Jour. Bot. & Kew Misc. 3° pl. 1, f. 1. 
Exsrccatt: Ellis, N. Am. Fungi 404; Rav. Fungi Car. 1: 6; Rav. Fungi Am. 206, 786; Underw. 
& Cook, Illust. Fungi 9; Thiim. Myc. Univ. 304); Rab.-Wint. Fungi Eur. 3646; Shear, N. Y. 
Fungi 24. 
13. PLEUROTOPSIS (P. Henn.) Earle, Bull. N. Y. Bot. Gard. 5: 
412. 1909. 
Marasmius § Pleurotopsis P. Henn. in E. & P. Nat. PA. 1**: 226. 1898. 
Pileus thin, membranous, reviving, sessile, resupinate when young; lamellae radiating 
from a central or eccentric point: spores hyaline: veil none. 
Type species, Marasmius spodoleucus Berk. 
Pileus white or whitish. 
Pileus 2 mm. broad; surface pruinose to glabrous. 
Hymenophore borne on an arachnoid mycelium. 1. P. arachnoidea. 
Hymenophore not borne as above. 2. P. calospora. 
Pileus 2 mm. broad; surface floccose. 3. P. niduliformis. 
Pileus 2-6 mm. broad; surface pruinose-floccose. 4. P. liliputiana, 
Pileus pale-brownish, 5-10 mm. broad, decorated with long fibers. 5. P. asperifolia. 
1. Pleurotopsis arachnoidea (Berk. & Curt.) Murrill. 
Marasmins arachnoideus Berk. & Curt. Jour. Linn. Soc, 10: 299. 1868. 
Pileus resupinate, adnate, very thin, 2 mm. broad; surface white, pruinose; lamellae few: 
stipe very short or obliterated, borne on an arachnoid mycelium. 
Type Locality: Cuba. 
Hasitat: On dead wood. 
DISTRIBUTION: Known only from the type locality. 
Le 
2. Pleurotopsis calospora (Pat.) Murrill. 
Crinipellis calosporus Pat.; Duss, Enum. Champ. Guad. 44. 1903. 
Pileus resupinate, becoming dimidiate, thin, membranous, 2 mm. broad; surface white, 
glabrescent, the cuticle consisting of elongate, tough, thick-walled cells 4-5 in diameter, 
margin smooth or sulcate: lamellae radiating from an eccentric point, distant, 5-7 in number, 
not interveined, thin, entire, whitish-yellow: spores ovoid, smooth, hyaline tinged with rose, 
10X7 u; cystidia clavate, thick-walled, hyaline, often encrusted above, 3310-15 pu. 
TYPE LOCALITY: Bains-Jaunes, Guadeloupe. 
Hapsirar: On dead twigs in woods. 
DISTRIBUTION: Known only from the type locality. 
3. Pleurotopsis niduliformis Murrill, sp. nov. 
Pileus minute, membranous, reviving, at first resupinate, becoming inverted cupuliform, 
sessile, vertically attached, regular, solitary to gregarious, about 2 mm. broad; surface floccose, 
white, smooth, margin concolorous, subentire, usually inflexed on drying: lamellae radiating 
from the point of attachment, rather distant, firm, narrow, undulate, white, the interspaces 
white, sometimes venose. 
Type collected on fallen dead twigs of Juniperus barbadensis in Bermuda, November 29- 
December 14, 1912, Brown, Britton, & Seaver 1350 (herb. N. Y. Bot. Gard.). 
DisTRIBUTION: Bermuda. 
