American Species of Marchantia. 281 



bounding cells more or less obscured by a resinous deposit; air- 

 chambers low, isodiametric or somewhat elongated, their outlines 

 very indistinct when viewed through the epidermis, present 

 everywhere, rows of photosynthetic cells usually two or three 

 cells long; compact ventral tissue about fifteen cells thick in 

 the median portion ; the walls sometimes pigmented, more or less 

 thickened and showing distinct pits, sclerotic cells scattered, 

 mostly fifteen to twenty in a cross-section, more abundant in the 

 median portion but often present in the wings, sometimes clearly 

 visible without sectioning, slime cells lacking; ventral scales in 

 two rows, the row of laminar scales more or less irregular but 

 tending to alternate with the median scales and not much nearer 

 the margin ; appendages of the median scales ovate, when well 

 developed mostly 0.3-0.45 mm. long and 0.25-0.3 mm. wide but 

 sometimes considerably smaller, apex apiculate, acute, or cuspi- 

 date, margin subentire or usually more or less closely denticulate 

 or dentate, the teeth irregular, mostly one or two cells long, 

 rarely larger and more lobe-like, cells showing a gradual and 

 slight decrease in size toward the margin, median cells usually 

 longer than broad, mostly 49-60/* long and 25-30/x wide, marginal 

 cells mostly 30-45/* long and 15-25/* wide, irregular but usually 

 with the long axis at right angles or nearly so to the margin, 

 cells containing oil-bodies apparently always lacking, male recep- 

 tacle borne on a stalk about 3 mm. long with two rhizoid-fur- 

 rows, the disc about 0.8 cm. wide, deeply four- to eight-lobed, the 

 lobes or rays palmately disposed (the basal sinus being very broad), 

 about 3 mm. long and i mm. wide, rounded at the apex and with 

 a thin wavy margin, ventral scales imbricated : female receptacle 

 borne on a stalk 1.5-2 cm. long, with two rhizoid-furrows and 

 a single broad dorsal band of air-chambers, the disc mostly 

 3-4 mm. broad, normally nine-lobed (but sometimes with five to 

 eight lobes), the lobes or rays 1-1.5 mm. long and about i mm. 

 wide, distinctly dilated at the truncate to emarginate apex, strongly 

 convex on upper surface, basal sinus broader than the others, 

 upper svirf ace of disc with a low median protuberance ; involucre 

 very delicate, irregularly lobed and crispate, otherwise entire or 

 slightly and irregularly crenulate ; pores yellowish brown, about 

 26/* in diameter, outer face bearing a series of very low ridges 

 not forming a network, margin narrow and often indistinct, less 

 than 2/* broad ; elaters about 8/* broad, bispiral : cupules spar- 

 ingly and irregularly denticulate to short-ciliate, the teeth being 

 projections of marginal cells or from one to four cells long, 

 epidermal papillae lacking. (Fig. 13.) 



The following specimens have been examined: 



Brazil : Rio de Janeiro, without date, G. Raddi (N. Y., type) ; 



without date, /. Milne (N. Y.) ; without definite locality or date, 



W.J.Bnrchell 1857 (N. Y.). 



Trans. Conn. Acad., Vol. XXI 19 1917 



