BY L. HOD WAY. 71 



Fofiftoinhrnnia dentata, St. — Closely creeping, mostly 

 1-2 cm., often reddish. Leaves closely imbricate, ascend- 

 ing, broadly ovate to retuse, 1.5-3 mm. long, margin 

 usually armed with about 12 bold spines, sometimes fewer 

 or much reduced, cells 40 x 50 ^. to 50 x 100 ^,. Rest 

 not seen. 



Common on heaths. 



JUNGERMANNIACEAE. 



Archegonia terminating the main stem or lateral 

 branch ; sometimes the lateral branch basal, and so re- 

 duced as to break down the technical distinction from 

 Metzgeriaccae. Leaves always jjresent (reduced to small 

 lateral lobes in Zoopsis), flat and expanded, entire or 

 variously armed, or divided, always arranged in two lateral 

 rows, generally a third ventral row of smaller leaves is 

 present. Sporopliyte surrounded at the base by a mem- 

 branous perianth, and an enlarged calyptra ; perianth 

 rarely absent. The base of the sporopliyte, with its ac- 

 companying envelopes, often more or less sunk in the 

 substance of the gametophyte shoot. When this tendency 

 is great this part of the stem develops a ventral, descend- 

 ing, fleshy bag, the marsupium. 



The family is very large. A few natural sub- 

 families may be separated out, but the bulk of the genera 

 do not present workable distinctions. Efforts have been 

 made to group them in accordance with differences in 

 structure of the perianth, but without a satisfying result. 

 The following treatment is almost upon these lines, but 

 depends more on leaf-shape. It is advanced not as being 

 more natural, but as a more workable key to help the 

 student. 



Sub-family Jungermannioideae. — Leaves succubous 

 rarely, almost transverse,, under-leaves absent, except 

 sometimes in the vicinity of the archegonia. 



1. Leaves entire, rarely retuse 2 



Leaves bifid 12 



2. Sporophyte with a simple perianth or 



calyptra 3 



Sporophyte inserted in a descending mar- 

 supium 9 



3. Perianth absent Gyiunowitriiim 



Perianth present 4 



4. Perianth 2-lipped, flat, terminal... Pldtjiocliihi 

 Perianth tubul ar 5 



