BARNES — NORTH AMERICAN MOSSES. 243 



B. Leaves not bordered. 



* Costate to the apex. 



Leaves acuminate, basal cells abruptly enlarged . A. irriguum, 374. 

 Leaves acuminate, basal cells not enlarged. 



Serrate throughout A. compactnm, 375. 



Entire or obscurely serrulate above. 

 Branches mostly erect, leaves loosely spreading when 



dry A. orthocladon, 374. 



Branches mostly spreading, tufts intricate, leaves im- 

 bricate when dry A. varinra,'^ 373. 



Leaves not acuminate, ovate to oblong lanceolate . A. flaviatile, 375. 



* * Costa ceasing at the middle or above. 



{A. eompacturri may be sought here.] 



Cells near middle of leaf 1 : 10-15. 

 Leaves long acuminate, apex sharp . . .A. riparinm,' 376. i- 

 Leaves acute, apex blunt ..... A. vacillans, 377. 

 Cells near middle of leaf less than 1 : 8. 

 Inner perichsetial leaves short acuminate (f| length). 



Leaves .65-.85 X .26-.36 mm A. serpens.' 373. 



Leaves 1.2-1.6 X •5-.7 mm A. Kochii, 6S5. 



Inner perichstial leaves subuliform acuminate, cells 



vermicular A. porphyrrhizon, 5S7. 



Kindberg has described four species belonging to this genus from bar- 

 ren specimens. A. fenestratum, App. 522, is probably not an Ambly- 

 stegium. A. speirophyllum, App. 523, may be doubtfully referred from 

 specimens in Can. Musci to A. irriguum. A. distantifolium, App. 529, 

 is very near A. irriguum. A. dissitifolium, App. 530, and A. sub-com- 

 paotum C. M. & Kindb., App. 531, are undoubtedly A. compactum 

 Miill. A. Holzingeri R. & C. is Hypnum (Limnobium) Closteri Aust. 

 A. Floridanum R. & C, App. 534, is so poorly characterized that I am 

 unable to separate it from A. riparium. A. Juratzkanum, App. 525, 

 A. hygrophilum (an Amblystegium?), App. 526, and A. Schlotthaueri, 

 App. 528, are subspecies of A. serpens, sec. Cardot, Hedwigia 32: 270, 

 271. 1893. A. homalostegium Jgr. & Sauerb., App. no. 536, is so doubt- 

 ful as an Amblystegium (ex desor.) that we omit it. 



1 Sypnwm radicate L. &,. J. Man. 373. 

 ' See Appendix, no. 532, 533. 

 ' See Appendix, no. 524-526, 528. 



