BARNES — NORTH AMERICAN MOSSES. 181 



II. Cells of the exothecium prosenchymatous ; seta often yellow; 

 casta usually broad and indistinct below. 



A. Seta red. 



Leaves from a steathing base, squarrose . . . D. crispa, 64. 

 Leaves not sheathing nor squarrose. 



Mostly erect, capsule cernuous .... D. snbnlata, 66. 



Secund, capsule erect ...... D. cnrTata, 67. 



B. Seta yellowish. 



Capsule symmetric, erect ..... D. Fitzgeraldi, 60. 



Capsule cernuous. 



Strumose D. cerviculata, 65." 



Not strumose D. heteromalla, 66. 



DICRANUM, p. 67.1 



In this genus the structure of the costa is of diagnostic value. It is 

 either composed of similar cells (homogeneous), or composed of large 

 parenchyma cells and small sclerenchyma cells (stereids). The large pa- 

 renchyma cells {guides = "Deuter" of Lorentz^) form a row (seldom double) 

 in the middle of the costa touching each other tangentially. They are 

 comparatively large, but little thickened and either empty or starch-bear- 

 ing. = 



I. Monoicous, stems radiculose only at base, costa long excurrent, 



homogeneous. 



Capsule erect, not strumose. 

 Striate and furrowed when dry . , . D. hyperboreum,* 64. 

 Neither striate nor furrowed when dry . . D. fnlvelluM, 68. 

 Capsule cernuous, strumose. 

 Leaf cells not papillose, capsule oblong-cylindric D. Starkii, 68. 



Leaf cells with papillse over partitions, capsule short-ovate. 



Leaves falcate-secuud D. falcatnin,° 68. 



Leaves spreading D. Bljtii, 68. 



1 Arranged by De. Bodnbt H. Teub. 



2 Pringsheim's Jahrb. f. wissensch. Bot. 6: 374. 

 'Limprioht: Die Lanbmoose 23. 



* See Appendix, no. 65. 

 " See Appendix, no. 65a, 



