262 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
or less thickened, pitted walls; mycorhiza sometimes present in the ventral 
tissue; ventral scales ovate to lunulate, more or less pigmented, cells containing 
oil bodies mostly 10 or fewer, scattered, appendages 1 or 2, narrowly to broadly 
ovate, mostly 0.25 to 0.45 mm. long and 0.15 to 0.3 mm. wide, entire or more or 
less dentate on the margin, the teeth very irregular, the apex acute to rounded, 
the cells in median portion mostly 40 to 80 X 30 to 50 u, the marginal somewhat 
smaller ; inflorescence paroicous, the antheridia forming a small indefinite group 
close to the peduncle of the female receptacle; ostioles low and inconspicuous: 
peduncle naked, often more or less pigmented with purple, 2 em. long when well 
developed ; disk of receptacle mostly 2 to 4 mm. across, the center hemispherical, 
smooth or nearly so but becoming rugose when dry, the lobes mostly four, short 
but distinct, extending obliquely downward, the margins and the deeply bifid 
involucre entire or irregularly sinuate or crenate; pseudoperianth mostly 8 to 
12-cleft, hyaline or more or less pigmented with yellow or purple, the divisions 
finally free, ovate to lanceolate; capsule opening by a circular line of dehiscence 
above the middle, the operculum coming off in one piece; spores yellow, 70 to 
110 » in diameter (mostly 80 to 90 w), with wavy wings 8 to 15 » wide along the 
edges, the entire surface covered with a system of numerous fine and irregular 
lines, sometimes anastomosing, the spherical face showing in addition a coarse 
and regular reticulum, the meshes mostly 16 to 18 » wide, inclosed by the 
marginal wing and a series of similar anastomosing ridges, each plane face 
usually with an irregular transverse ridge distinct from the wings; elaters 
yellow, straight or somewhat curved, mostly 140 to 200 w long (rarely 300 ,») 
and 10 to 12 » wide, slightly tapering toward the blunt ends, the median por- 
tion with 2 (very rarely 3) spirals, one or both of the ends often with a single 
spiral for a variable distance. 
The present species is widely distributed in eastern North America, its known 
range extending from Maine and Ontario to Georgia and Alabama, with a west- 
ward extension to INinois, Missouri, and Texas. So far as the writer has been 
able to learn, all reports from localities outside this area have been based on 
incorrect determinations. The plants are largely, if not entirely, confined to the 
lowlands. They prefer relatively damp soil and may often be found in old fields, 
along roadside banks, or among rocks bordering streams. On account of their 
delicacy they are not well fitted for a xerophytic environment. In most cases 
the plants grow scattered or in small clusters but they sometimes form ex- 
tensive mats, the numerous receptacles on their slender stalks giving them a dis- 
tinctive and beautiful appearance under favorable conditions. There is little 
danger of confusing A. tenella with other members of the genus, since none of 
our species, with the possible exception of A, echinella, are known to encroach 
upen its range. When sterile, however, it has often been confused with Re- 
boulia hemisphaerica and Grimaldia fragrans, to both of which it bears a cer- 
tain resemblance. The following specimens have been examined: 
Ontario: Windsor, 1892, J. Macoun 404 (N. Y.). 
MAINE: Buckfield, 1877, J. A. Allen (Y.) ; Monmouth, Merrill 3 (N. Y., ¥.); 
Kittery Point, Thaxter (H., Y.). First reported from Maine by the writer 
(Rhodora 5: 170. 1903), no localities being given. 
New HAmpsuHireE: Cornish, 1904, Haynes 723b (Y.; listed by the writer in 
Rhodora 7: 58, 1905). 
VERMONT: Jerico, Wvans (Y.) ; Newfane, Grout (Y.) ; East Pownal, Lorenz 167 
(N. Y.) ; Woodstock, Kittridge (N. Y.). Recorded by C. D. Howe (Contr, Bot. 
Vermont 3: 9. 1899); an earlier record of Frost seems to have been based on 
an incorrect determination. 
MAassacHusETts: Amherst, 1871, Jesup (C.); Amesbury, Huntington (C. C. 
H., Y.); Wellesley, Hallowell (H.), Cummings (N. Y.); Bridgewater, Crocker 
