A. W. Evans — North American Species of Frullania. 5 



Lobule inflated throughout its whole extent or nearly so, connected 

 with the lobe by a short fold approximately at right angles to 

 the stem. 



Lobule about as broad as long. 



Underleaves not cordate at base ; perianth typically 

 triangular or trapezoidal in section, usually with 

 tubercles or supplementary ridges or both. 



Subgenus IL Tkachtcolba. 



Underleaves cordate at base ; perianth simply trigonous 

 and smooth. Subgenus III. Homotropantha. 



Lobule decidedly longer than broad; perianth simply tri- 

 gonous and smooth. 



Inflorescence dioicous ; perianth terminal on a sim- 

 ple lateral branch. 



Subgenus IV. Thiopsiblla. 



Inflorescence autoicous ; perianth terminal on the 

 stem or a main branch. 



Subgenus V. Diastoloba. 



Subgenus I.— CHONANTHELIA Spruce. 



Represented by the single species : — 

 1. Frullania arietina Tayl. in G. L. et N. Syn. Hep., 413. 1845. 



Plate I. figs. 1-6. 



Paroicous : plants closely appressed to matrix, green, often tinged 

 with yellow or brown : stems irregularly branched : leaves imbri- 

 cated, the lobe orbicular-ovate, arching over the stem but scarcely 

 cordate at base, plane or slightly decurved at the rounded apex, con- 

 nected with the lobule by a long fold, subparallel to the stem ,• lobule 

 tubulose-inflated in the upper half only, the lower forming a plane, 

 iiTegular or subrhomboidal, subentire expansion ; stylus minute, sub- 

 ulate : underleaves contiguous or subimbricated, plane, oi'bicular, 

 scarcely or not at all auriculate at base, shortly bifid at apex (^-^) 

 with subobtuse lobes and sinus, entire or slightly crenulate on the 

 margins ; leaf -cells in middle of lobe rather thin-walled but with 

 conspicuous trigones; toward the base the trigones are still more con- 

 spicuous and intermediate thickenings become abundant : $ inflores- 

 cence terminal on a short lateral branch ; bracts in one to three 

 pairs, highly connate with the corresponding bracteoles, unequally 

 bifid, the lobe ovate, acute, sparingly toothed, lobule ovate, acute, 

 narrower than the lobe but similarly toothed and bearing a dis- 

 tinct tooth or stylus at or below the middle of its inner edge ; brae- 



