610 Evans: REPORT OF THE HEPATICAE OF ALASKA 
a greater dilation at the antical base of the lobe so that the margin 
arches beyond the stem. The leaves of the flagella are distant 
and subequally bilobed. So far as measurements go the two species 
are much the same, the lobes of the stem-leaves in R. prolifera 
measuring about 1X0.85 mm., the lobules about 0.5 X0.4 mm., 
and the lobes of the flagella about 0.20.15 mm. In the stem- 
leaves the cells of the lobes average about 12 » in diameter along 
the antical margin, about 18 w in the middle, and about 20 uw at 
the base, so that these, too, agree closely with the cell-measurements 
in R. polyclada; and an equally close agreement may be found 
between the characters derived from the cell-walls. 
65. PLEUROZIA PURPUREA (Lightf.) Lindb. 
Jungermannia purpurea Lightf. Fl. Scotica 778. 1777. 
Jungermannia cochleariformis Hook. Brit. Jung. pl. 68. 1814. 
Radula cochleariformis Dumort. Syll. Jung. 38. 1831. | 
Pleurozia cochleariformis Dumort. Recueil d’Obs. sur les Jung. 15. 
1835. 
Physiotium cochleariforme Nees, Naturg. Europ. Leberm. 3: 79- 
1838. 
Pleurozia purpurea Lindb. Musc. Scand. 3. 1879. 
In very wet places, Brownson Bay (482); Metlakatla (177); 
Nichols Bay (376). New to America. The species was originally 
described from specimens collected in Scotland, where it is now 
known to be widely distributed. It is known also from Ireland, 
the Faroe Islands, and Norway, and reappears in the Himalyas 
and in the Hawaiian Islands. Its geographical distribution, 
therefore, coincides in most respects with that of Amastrepta 
orcadensis, except that its range in Europe is more circumscribed. 
The genus Pleuwrozia is one of the most clearly defined genera of 
the Hepaticae and includes ten species, all of which were known 
to Jack when he monographed the genus in 1886.* With the 
exception of P. purpurea the species are confined to tropical regions, 
four being cited by Jack from the Hawaiian Islands. The plants 
are all of large size, the stems in some of the species attaining a 
oe of I2cm., — all are characterized by a more or less marked 
* Monographie der y chiteiagsinune Pivccinn: Hedwigia 25: 49-87. Pl. 
I-I0. 1886, 
