Riccia sullivantii

Riccia sullivantii Aust. Proc. Acad. Phila. 1869: 233. 1869
Riccia Jiuitans terrestris Aust. Hep. Bor.-Am. 37. 1873.
Riccia fiuitans SuUivantii Underw. Bull. 111. Lab, Nat. Hist. 2: 28. 1884.
Riccia Huebeneriana Underw. Bot. Gaz. 19: 276. 1894. Not R. Huebeneriana Lindenb. 1837.
Ricciella SuUivantii Evans, Rhodora 9: 56. 1907.
Thalli terricolous, small or medium-sized, forming rosettes 10-20 mm. in diameter or irregularly gregarious, mostly 3-5 times dichotomous, light-green or darkish-green above, concolorous or rarely purple below and on margins, more or less costate-carinate, the dorsal surface remaining rather smooth or sometimes spongiose-alveolate with age, the branches often widely spreading; main segments oblong or sublinear to obcuneate-quadrate, 0.75-1.5 mm. wide; terminal segments oblong, elliptic, or quadrate-obovate, obtuse or emarginate; margins obtuse or subacute, usually ascending; median sulcus broad and rather shallow, usually well defined; scales rudimentary; tranverse sections subelliptic or fusiform, mostly 2-4 times as broad as high; dorsal epidermis unistratose, persistent or sometimes collabent and disintegrated over air-chambers with age, the cells mostly 50-120 ;u in maximum diameter; air chambers elongate-polyhedral or claviform, separated by unistratose lamellae and showing 1-3 series in a transverse section. Monoicous; antheridial ostioles elevated 100-175 ju; capsules usually numerous, forming hemispheric or subglobose protuberances 500-750 /i in diameter on the ventral surface; spores brown or yellowish-brown, 50-78 n in maximum diameter, angular, with a margin 3-6 ju wide or the margin often cut into crests or papillae or sometimes almost wanting, the outer faces with areolae 8-13 fi broad, 5-8 areolae measuring the width of the face, the angles of the meshes scarcely elevated or often lifted into obtuse or truncate, nearly smooth or cristulate-muriculate papillae 2-3 ^ high, the inner faces similarly but a little less strongly marked, sometimes with less perfect areolae.
Type i,ocality: Closter, New Jersey.
Distribution: Quebec and Maine to Wisconsin, Missouri, and Florida; Cuba.