102 HYPNACEAE 



distinguished by the acute leaves, strong single costa and rough 

 seta. 



Key 



I — Alar cells large and conspicuous, clear, hyaline or colored, forming 

 distinct decurrent auricles; outer layer of stem cells much en- 

 larged 2 



Alar cells thick-walled, less distinctly inflated, granulose to sub- 

 opaque, often colored; outer layer of stem cells not enlarged 3 



2 — Alar cells hyaline and thin-walled; costa usually reaching the middle 



of leaf; dioicous ochraceum 



Alar cells usually colored and thick-walled, except the outer row or 

 two, which are usually thin-walled and often hyaline; costa 



double, short and faint; monoicous eugyrium 



3 — Costa single, often forking and often reaching above middle 4 



Costa short and double; leaves denticulate at apex dilatatum 



4 — Plants minute; stem leaves flat, obtuse to suborbicular 5 



Plants larger; leaves concave, oval-oblong palastre 



5 — Leaves flat, entire closteri 



Leaves concave, obsoletely denticulate Smithii 



H. closteri (Aust.) Grout. "On rocks in streams about Clos- 

 ter, N. J.," Muse. App. 439. 



H. dilatatum (Wils.) Loeske. " On rocks along streams, 

 northern N. J., rare," Muse. App. 436 (as Hypnwn molle); 

 Darien, Bry. Ct. Summer. 



H. eugyrium (B. & S.) Loeske. Hamden, Beacon Falls, etc., 

 Bry. Ct. Spring. 



Var. Mackayi (Sch.) Broth. New Haven, Bry. Ct. 



H. ochraceum (Turn.) Loeske. "On rocks along streams' 

 northern N. J.," Muse. App. 437; Yonkers, Howe, Bx! Spring- 

 summer. 



H. palustre (Huds.) Loeske. "On rocks in mountain rivulets, 

 northern N. J., rare," Muse. App. 435. 



H. Smithii (Sw.) Broth. {Hyp. arcticam Sommerf.) "On 

 rocks along rivulets near Closter, N. J.," L. & J. Manual: 400. 

 This is probably an error in determination. The N. J. plants 

 are probably H. closteri. I have not been able to find out 

 conclusively. 



Scorpidium scorpioides (L.) Limpr. Margins of pond, Marksboro, N. J. 

 Wiegmann. 



