ARCHILEJEUNEA SELLOWIANA 125 
is sometimes composed of two superposed cells, instead of a single 
cell as is usual in the species. They show, however, even on 
robust stems, no other approach to either of the following species. 
2. ARCHILEJEUNEA SELLOWIANA Steph. 
PLATE 16, FIGS, 12-20 
Phragmicoma xanthocarpa Aust. Hep. Bor.-Amer. 95b. ۰ 
Not Jungermannia xanthocarpa Lehm. & Lindenb.; Lehmann, 
Pugillus, 5: 8. 1832 (Lejunea xanthocarpa Lehm. € Lindenb. ; 
G. L. € N. Syn. Hep. 330. 1845). 
Archilejeunea Sellowiana Steph. Hedwigia, 34: 62. 1895. 
Lejeunea velata Gottsche ; Stephani, /. c. (as synonym). 
Pale glaucous-green or whitish, growing in broad depressed 
mats: stems prostrate, often radiating from a center, 0.17 mm. in 
diameter, closely appressed to matrix, irregularly branched : 
rhizoids abundant: leaves closely imbricated, the lobe widely 
spreading almost at right angles with axis, ovate-oblong, some- 
times slightly falcate, plane or slightly convex, 1.2 mm. long and 
0.95 mm. wide on robust individuals, slightly revolute at the 
rounded apex, margin entire or subcrenulate from projecting cells, 
antical margin rounded at base and arching across or just beyond 
axis; lobule somewhat inflated toward base, oblong, 0.6 mm. 
long, 0.25 mm. wide, keel slightly arched, forming a distinct but 
very obtuse angle with postical margin, free margin curved, 
slightly inflexed near base, otherwise plane, apex acuminate, 
sometimes hamately curved, the apical tooth mostly three to cight 
cells long and two to four cells wide at base, ending in a single 
row of two or three cells, sinus beyond apex deep and rounded 
then passing very obliquely into postical margin, free margin of 
lobule, except for apical tooth usually entire but, in rare Cases, 
poorly developed ; cells of lobe convex with rather thick project- 
ing walls and thin vertical walls, trigones large, acuminate to 
obtuse, intermediate thickenings not infrequent in middle of lobe 
and abundant toward base, mostly circular in outline, cells at edge 
of lobe 12 p in diameter, in the middle and at the base 18 p: un- 
derleaves contiguous to imbricated, broadly orbicular to reniform, 
0.6 mm. long, 0.7 mm. wide, rounded, truncate or retuse at the 
apex, rounded or subcordate at base, attached by a slightly curved 
line of insertion : inflorescence autoicous: 9 inflorescence usually 
borne on a short branch, more rarely on a leading branch, inno- 
