VAN ESELTINE—SELAGINELLA RUPESTRIS ALLIES. 163 
The following specimens have been examined: 
Texas: Burnett County, Reverchon 1632 (N, M, Y).?_- Hudson Mountain, 
Gillespie County, Jermy 342 (N, M). Newton County, Holmes & 
Fetherolf, January, 1903 (N). Montgomery County, Thurow 8 (N). 
Prairie View, Waller County, Thurow, October 26, 1915 (N). Llano, 
Lindheimer 76 (M); Plank (Y). Marble Falls, Plank (Y). Austin, 
Long, March, 1900 (Y), and February, 1901 (Y). Localities wanting, 
Drummond 852 (Y); Riddell 16 (Y). 
DISTRIBUTION: -Central and eastern Texas. probably through southern 
Louisiana. 
The rugose-reticulate megaspores differentiate this plant from all others of 
the southeastern United States, while the very slender, erect shoots are in 
rather marked contrast with any of the other Texan and New Mexican species. 
Selaginella rupincola, with which this species might possibly be confused, is a 
larger plant, with longer sete, thicker stems, and megaspores with a raised 
ring circumscribing the ends of the commissural ridges. 
There is a brief manuscript description of this species (under Lycopodium) 
by Riddell in the Gray Herbarium. 
EXPLANATION OF PLATE 15.—Type specimen of Selaginella riddellii. Natural size. 
2. Selaginella arenicola Underw. Bull. Torrey Club 25: 511. 1898. 
Puates 16,17. Figure 64. 
Selaginella arenaria Underw. Bull. Torrey Club 25: 129. 1898, not Baker, 
1883. 
Plants erect, fasciculate, 5 to 10 cm, high, somewhat rigid; rhizophores 
abundant, arising only from the base of the shoots; stems (including leaves) 
up to 1 mm. thick, rigid, freely branched at intervals of 7 to 10 mm.; primary 
branches few (3 to 5), 4 to 8 em. long, with few short branchlets, these 5 to 
10 mm. long, simple, strictly ascending, incurved ; leaves 6-ranked, appressed, 
slightly imbricate, in the younger stages glaucous green, in age becoming cinere- 
ous brown, thickish, papillose-roughened, flat above, slightly convex beneath, 
deeply sulcate dorsally in a median line up to the apex, linear-deltoid from a 
long decurrent base, minutely 7 to 14-ciliate on the margin, bearing a clump 
of cilia on the decurrent base; longest leaves 1.2 mm. long, about 0.8 mm, wide 
at the base; cilia 0.083 to 0.06 mm. long; sete up to 0.8 mm. long, 0.03 to 0.06 
mm. thick, white with yellowish base, spinulose-serrulate throughout. 
Spikes terminal on the shoots and upper branches, quadrangular, 1.5 to 2 cm. 
long; sporophylls elongate-triangular from an auriculate base (auricles broadly 
rounded-triangular) acute, in the younger stages glaucous green, in age be- 
coming pale brown, somewhat cymbiform, about 1.2 mm. long, 0.66 mm. wide 
at the base, 15 to 25-ciliate on the margin, deltoid. 
Megasporangia in the axils of the lower sporophylls, 0.6 mm. in diameter ; 
megaspores crustaceous, punctate on the commissural side, irregularly and 
minutely punctulate on the opposite side, chalk-white, 0.4 mm. in diameter ; 
microsporangia in the axils of the upper sporophylls, flattened, reniform, the 
widest diameter 0.6 mm.; microspores red to orange, the widest diameter 
0.036 mm. 
1 Capitals in parentheses designate the herbarium in which the specimen ex- 
amined is deposited, as follows: (N), U. S. National Herbarium; (G), Gray 
Herbarium of Harvard University; (Y), herbarium of the New York Botanicai 
Garden; (M), herbarium of the Missouri Botanical Garden. 
