224 American Midland Naturalist Monograph No. 6 



base, slightly concave, non-plicate, margin plane and entire; costa none or 

 very short and weak; median leaf-cells rhomboid-hexagonal or oblong-hexag- 

 onal, 2-4 (-8) :1, the basal rather lax, parenchymatous, the alar quadrate; inner 

 perichaetial leaves erect, basally sheathing, lanceolate to lance-oblong, long- 

 acuminate, ecostate, or with the costa ending in or above mid-leaf: seta 5-12 

 mm long, drying flattened, yellowish-red to castaneous; capsule mostly erect 

 and symmetric, rarely secund and cemuous, obovate to oblong-cylindric, when 

 dry and empty constricted below the wide mouth, smooth; annulus present; 

 peristome-teeth narrowly lance-ovate, basally confluent, yellowish, bordered, 

 dorsally cross-striate, above pale and papillose, densely trabeculate below; inner 

 peristome pale or yellow, basal membrane high, segments entire or but slightly 

 split, cilia rarely 1-3 and complete, mostly solitary and rudimentary or none, 

 non-appendiculate; lid high-convex, obtuse to acute; spores small. 



A genus of 9 species, confined to the Northern Hemisphere, occurring 

 on trees and rocks; 5 species in North America; two sp>ecies occurring in our 

 range. 



Key to the Species 



A. Leaves not narrowed to insertion; inner perichaetial leaves irregularly toothed 



-... 1. A. mtnutissima 



A. Leaves narrowed to the insertion B 



B. On tree bases; leaves lanceolate to linear-lanceolate; inner perichaetial leaves entire 

 3. A. subtilis 



B. On rocks; leaves ovate to lance-ovate; inner perichaetial leaves denticulate above 



2. A. confervoides 



L Amblystegiella MiNUTissiMA (Sullivant and Lesquereux) 



Nichols 



(Hypnum minutissimum Sullivant and Lesquereux; 

 Amblysteginm minutissimum Jaeger) 



Minute, pale green: stems prostrate, short, up to about 1 cm long, with 

 radicles in fascicles, the branches occurring sub pinnately and spreading to 

 erect; leaves loose, narrowly triangular-lanceolate, broadest and not narrowed 

 at base, 0.3-0.4 mm long, more or less serrulate, ecostate or very faintlv marked 

 with striae; leaf -cells large, oblong, about 4-8:1, the marginal alar cells about 

 2:1; capsule minute, about 0.5 mm long, ovoid, symmetric or slightly curved, 

 constricted below the mouth and turbinate when dry and empty, thin-walled, 

 yellowish; seta slender, 4 or 5 mm long; teeth yellowish, hyaline-bordered; 

 cilia as long as segments and 1 or 2 in number; annulus 2-seriate, persistent; 

 lid conic, apiculate-rostrate, about one-half to nearly as long as urn; spores 

 ripe in summer. 



On rocks and stones in shaded ravines, said to prefer limestone, from New 

 Jersey and Pennsylvania westward to Illinois, Ontario, the Rocky Mountains 

 and British Columbia. Rare in our region. 



Rare in our region. Huntingdon Co.: Alexandria. T. C. Porter. (Porter's Cata- 

 logue ) . 



