April, 1905.] 
Key to Liverworts. 
313 
thus modified and remaining at the bottom of the perianth rep- 
resents the calyptra. It is soft and hyaline and in most cases 
shorter than the perianth and not connate with it. 
It may be added that any suggestions in regard to the 
improvement of this key will be thankfully received. 
All liverworts are usually divided into two artificial groups, 
the foliose and frondose, which are then subdivided as follows: 
Plant-body a leafy axis (Jungermanniaceae). 1 
Plant-body a thallus. 30. 
1. Leaves incubous. 2. 
Leaves succubous. 13. 
2. Leaves compile at e-bilobed or with a small lower lobe. 3. 
Leaves not compHcate-bilobed or with a small lower lobe. 7. 
3. Lower lobe incurved-ventricose or saccate, seldom expanded. 4. 
Lower lobe quadrate or roundish. 6. 
4. Lower lobe incurved, more or less ventricose. Lcjeiinia. 
Lower lobe saccate, seldom expanded. 5. 
5. Branches intra- axillary, the leaves on either side free. Friillania. 
Branches lateral, a basal leaf borne partly on the stem, partly on 
the branch. Jnbida. 
G. Lower leaf-lobe quadrate. Raditla. 
Lower leaf-lobe roundish. Porclla. 
7. Leaf-divisions numerous and capillary. 8. 
Leaf-divisions not numerous and capillary. 9. 
8. Leaves bilobed, lobes subdivided and with ciliate margins. Perianth 
present, terminating short bi'anches, smooth, obovate, mouth 
connivent, plicate-denticulate. Ptilidium. 
Leaves 4-.5-divided, divisions setaceously multifid and fringed. 
Perianth none or rather forming together with the calyptra and 
involucre a terminal or axillary, fleshy and hairy torus. 
T richocolea. 
9. Leaves deeply bilobed and 3-ranked (underleaves being similar to 
leaves. Herbcrta. 
Leaves not bilobed and 3-ranked. 10. 
10. Leaves entire (sometimes retuse) or 2-3-toothed. 11. 
Leaves 2-4-cleft or parted. 12. 
11. Leaves entire (sometimes retuse). Kantia. 
Leaves 2-3-toothed, Bazzania. 
12. Leaves 3-(or seldom 4) parted; diyisions capillary, formed by one 
row of cells. Blepharostoma. 
Leaves palmately 2-4-cleft or -parted; divisions formed by more 
than one row of cells. Lepidozia. 
13. Capsule opening irregularly into 4 irregular or dentate valves; plant- 
body pseudofoliaceous. Fossombronia. 
Capsule opening regularly into 4 regular valves; plant body foli- 
aceous. 14. 
14. Perianth absent; leaves closely imbricate and 2-ranked on short 
julaceous stems. Gymnomitrium. 
Perianth present. 15. 
15. Perianth connate to the middle or more with the involucral leaves. 16. 
Perianth free or connate with calyptra. 17. 
10. Perianth connate to near the summit; leaves complicate-bilobed. 
Marsitpella. 
Perianth connate to the middle; leaves entire or nearly so. Nardia. 
17. Perianth pendant, saccate; leaves bilobed, extending horizontally 
and at right angles from the stem; underleaves 2-cleft. Geocalyx. 
Perianth upright ; underleaves none or ovate-lanceolate or 2-4-cleft. 18. 
