Se ee Sg are 
EvANS: REPORT ON THE HEPATICAE OF ALASKA 611 
purple pigmentation. One of the most remarkable features of the 
genus is found in the apical cell, which has only two cutting faces 
instead of three, as in all the other genera of the leafy hepatics. 
This interesting peculiarity was first pointed out by Goebel,* 
who naturally associated with it the total lack of underleaves. 
Even more interesting features, however, are found in the leaves. 
These, except in a single species, are bilobed and complicate, the 
postical lobe forming a highly complex water-sac, the mouth 
of which is closed by a complicated valve. The details of this 
singular structure are fully described by Goebel, in the place just 
quoted, so that it is unnecessary to include an account of them here. 
The only species with which P. purpurea need be especially 
compared are P. gigantea (Web.) Lindb.f and P. conchaefolia 
(Hook. & Wils.) Aust. both of which occur in the Hawaiian 
Islands, although not confined to them. In all three species the 
entire postical lobe takes part in the formation of the water-sac. 
In P. purpurea, however, the antical lobe is shortly bilobed at the 
apex with triangular spinose-dentate lobes, while in P. gigantea 
the antical lobe is usually quite undivided and much less sharply 
toothed. In P. conchaefolia the postical lobe is relatively much 
larger than in P. purpurea, instead of being about half as long, 
while the antical lobe is truncate or only slightly emarginate and 
otherwise entire in the apical portion. A full description of P. 
purpurea, with figures, is given by Macvicar,$ and an account of a 
well-developed perianth with its bracts has recently been published 
by Schiffner.| 
66. PORELLA NAVICULARIS (Lehm. & Lindenb.) Lindb. 
On trees. Brownson Bay (479); Kanagunut Island (47); Port 
San Antonio (Foster 1121); Ratz Harbor (296); Shipley Bay (768); 
Tam Gas Harbor (135). Previously reported by Gottsche, Lin- 
denberg, and Nees von Esenbeck (5, p. 297, as Madotheca navicu- 
laris), Stephani (14, p. 98, as M. navicularis), and the writer 
(3, p. 313). ieee ic ree 
* Flora 7: 453. 1803. 
t Hep. Scand. Exs. No. 5. 1874 (=Jungermannia gigantea Web.). 
t Bull. Torrey Club 5:17. 1874 (= Jungermannia conchaefolia Hook. & Wils.). 
§ Student’s Handb. British Hepat. 394. f. I-3. I9QI2. 
| Oesterr. Bot. Zeitschr. 62: 11. f. I-3. I912. 
