246 BULLETIN OF THE UNIVERSITY OP WISCONSIN. 



Acute or short apiculate, alar cells few, large . H. palustre, 398. 

 Obtuse, entire, alar cells hyaline . . . H. cuspidatuiii, 403. 



2. Alar cells scar'celif different or quadrate or rectangular, not 



abruptly enlarged. 



* Leaves thin, glossy, open; plants mostly small, x>'>'Ostrate or with 



ascending branches. 



Leaves squarrose, acuminate. 

 Sub-serrulate all around, lid apiculate . . H. hispiduhim, 378. 

 Entire except the acumen, lid obtuse . . . H. Macouuii, 539. 

 Leaves loosely imbricate, obtuse or acute. 

 Serrulate, at least above. 

 Nearly as broad as long, obtuse or apiculate. 



Alar cells small, not forming distinct auricles, 



others 1 : 8-10 H. molle, 399. 



Alar cells large, forming distinct auricles, others 



much longer than preceding . . H. (iilatatum,^ 601. 



Nearly twice as long as broad, acute, point often half 



twisted H. alpestre, 399. 



Entire. 

 Leaves close set, ovate (1:2). . . . H. Norvegicum, 581. 

 Leaves more distant, rotund .... H. Ooulardi, 585. 



* * Leaves firm; plants very large, mostly 1-2 pinnate, erect 



or ascending. 

 Paraphyllia none. 



Capsule smooth when dry. 

 Leaves obtuse. 

 Olive or grayish green, 1-2-pinnate, leaves open H. Schreberi, 404. 

 Dirty green to dark brown, almost simple, leaves 



closely appressed H. trifarium, 405, 



Leaves abruptly apiculate, plants pale green . . H. piirum, 594. 

 Capsule plicate when dry, plants dark green to reddish 



brown ....... H. scoi'pioides,^ 406. 



Capsule unknown; plants dark yellow and greenish, branches 



julaceous, few, fastigiate, leaves short apiculate H. turgescens, 406. 

 Paraphyllia present ...... H. Alaskanuiu, 405. 



1 iif. circuUfoUum C. M. & Kindb., Appendix, uo. 583, belonging to this division and de- 

 scribed from sterile specimens, is related to H. dilatatum Wils. 

 'See Appendix, no. 599. 



