521 
Exsicc. Hep. Bor-Am. 91 b. 
Hep. Am. 96 (as Porella platyphylla), 150 (as Porella Roellii, 
var.). 
Can. Hep. 99 (as Porella dentata). 
On moist rocks, stones in streams, and bases of trees in densely 
shaded places. Widely distributed and extremely variable accord- 
ing to habitat. Apparently rare in eastern North America, but 
common on the Pacific Coast. Connecticut (Eaton) ; Ohio (Sul- 
livant) ; Texas and New Mexico (Wright); Montana (R. S. Wil- 
liams) ; Idaho (Leiberg) ; British Columbia (Macoun) ; Alaska 
(Miss Grace E. Cooley) ; California (Bolander, Parish, Howe). 
Our determination is based upon the drawing (acccompanying 
G. & R. Hep. Eur. no. 371) of the original plant from the bed of 
the river Bober, near Hirschberg, Silesia, and upon European 
Specimens and the descriptions of authors. 
The name dentata, applied by Hartman in 1832 (Skand. Fl. — 
354, 2d ed.) to what he considered a variety of Jungermania 
platyphylla was taken up for the above species by Lindberg in 
1869, but was abandoned by him ten years later without explana- 
tions. Hartman’s description of his variety dentata is quite inade- 
quate for its proper identification and as we have failed in our 
efforts to see his original specimens, if such exist, we prefer to 
adhere to the first name which was accompanied by an intelligible 
diagnosis. 
5. PoreLLa pLatypHyLia (L.) Lindb. Act. Soc. Scien. Fenn. 
9: 339. 1869. 
Jungermannia platyphylla L. Sp. Pl. 2: 1134. 1753. 
Jungermannia platyphylloidea Schwein. Spec. Fl. Am. Sept. 
Crypt. 9. 1821. 
Madotheca platyphylla Dumort. Comm. Bot. 111. 1822. 
Madotheca navicularis Nees, Naturgesch. Eur. Leberm. 3: 176 
Pp: P1838. 4 
Porella thuja Lindb. Act. Soc. Scien. Fenn. 9: 337. 1869. 
Dull or most rarely with a slight lustre, opaque or a little pel- 
lucid, yellowish to very dark green, rather rigid: stems somewhat 
regularly or irregularly 1—-3-pinnate, 3-8 cm. long, procumbent, 
