—63 — 
cylindric, ribbed, mostly small, exannulate ; peristome double, single or 
absent ; lid conic or rostrate; calyptra cucullate, smooth or rarely hairy. 
Type species Z. conoideus; European. 
Eleven North American species are known of which eight are Mexican, 
1. Zygodon viridissimus (Dicks.) Brown Trans. Linn. vSoc. 12; (1.) 575. 1819. 
Bryum viridissimum Dicks. Fasc. PL Crypt. 4: 9. PL 10. f. 18. 1801. 
Plants bright green, 1-2 cm. high. Stems tomentose with papillose radi- 
cles often having 4-5-celled propagulae; branches and leaves secund, 1.5-2. 5 
mm. long, lanceolate, apiculate; vein ending below the apex, papillose above, 
smooth below ; cells papillose on both sides, upper rounded, thick-walled, 
lower rectangular and smooth. Perichaetial leaves smaller. Dioicous. 
Seta 3-5 mm. long, terminal becoming lateral; capsule 1.5-2 mm., pyriform- 
cylindric, ribbed when old, walls with thickened ridges ; mouth red, small ; 
annulus none; peristome none; spores rough, .013-016 mm., maturing in 
August; capsules persistent. 
Type locality: England. 
Distribution : On trees throughout North and Central Europe. Rare in 
North America; in the mountains of Northern New York and Virginia to 
North Carolina and Georgia. 
Illustrations: Dickson 1 . c. PI. 10. f. 18. 1801. Eng. Bot. pi. 1583. 1805. 
Hook & Tayl. Muse. Brit. Pi. 6, 1818. Br. Eu. 3, PI 206. 1850. Mem. Torrey 
Bot. Club pi. 80, 1893. 
First collected on White Top, Va. , May 29, 1892, by J. K. Small and E. 
G. Britton, growing on Picea rubra with Dicranum longifolium, Herberta 
adunca , etc. Later found at base of trees in the Adirondack Mountains, N 9 
Y., near Adirondack Lodge, Sept. 1892, and Adirondack Reserve, Sept. 1898, 
forming bright green sterile cushions, mixed with various other mosses. 
2. Zygodon rupestris Lindb. Milde Bryol. Siles. 164. 1869. 
Zygodon viridissimus var. rupestris Hartm. Skand. FI. 9 ed. 52. 1864. 
Plants in dense brown cushions matted with radicles at base; stems 
1-3 cm. high, bifurcating; branches erector slightly secund at apex; leaves 
crowded, slightly circinnate when dry, not recurved but speading when 
moist, 1-1.5 mm. long, ligulate-lanceolate acuminate, carinate; costa ending 
below the sharply subulate apex ; margins entire; cells round, thick-walled, 
minutely papillose, basal cells larger, oblong, clear. Dioicous. Fruit 
unknown ! Reproducing by clusters of 3-5-celled brown propagulce borne 
on radicles in the axils of the leaves. 
Type locality : Scandinavia, Lindberg. 
Distribution ; On calcareous rocksjin mountains of Central and Northern 
Europe. In America, Hudson’s Bay and Vancouver Island. Also on steep 
cliffs, Cascade Mountains, Washington, J. A. Allen. 
Exsiccatae: Drummond, North American Mosses No. 27. 1828. Allen’s 
Mosses of the Cascade Mountains No. 46. 1898. 
Illustrations; The gemmae correspond with those figured by Correns 
Unt. 1 1 7. f. 71 for Z. viridissimus f. borealis! 
