682 HEPATIC^:. (LIVERWORTS.) 



ORDER 140. HEPATIC^E. (LIVERWORTS,*) 



Moss-like plants, of a loose cellular texture, usually procumbent, and emit- 

 ting rootlets from beneath ; the calyptra not separating from the base, but 

 usually rupturing at the apex; the capsule not opening by a lid, containing 

 spores usually mixed with elaters (which are thin thread-like cells, contain- 

 ing one or two spiral fibres). Vegetation sometimes frondose, i. e. the 

 stem and leaves confluent into an expanded leaf-like mass; sometimes 

 foliaceous, when the leaves are distinct from the stem as in true Mosses, 

 entire or cleft, 2-ranked, and often with an imperfect or rudimentary row 

 (amphigastrid) on the under side of the stem. Reproductive organs of two 

 kinds, viz. antheridia and pistillidia, much as in Mosses (p. 607), variously 

 situated. The matured pistillidium forms the capsule, which is immersed 

 in or sessile upon the frond, or borne on a long cellular pedicel, or 

 attached to the under side of disk-like peduncled receptacles, and dehisces 

 by irregular openings, by revolute segments at its apex, or lengthwise by 

 2-4 valves: a columella is rarely present. The perianth is a tubular 

 organ (sometimes absent), enclosing the calyptra, which is always present, 

 and directly includes the pistillidium. Surrounding the perianth is the 

 involucre (occasionally wanting), also a tubular organ, or leaves of particu- 

 lar forms. The antheridia in the foliaceous species are situated in the 

 axils of perigonial leaves ; in -the frondose species, scattered within the 

 substance, or sessile upon the surface of the frond, or immersed in sessile 

 or peduncled disk-like receptacles. 



Artificial Analysis of the Genera. 



I. Vegetation frondose (stem and leaves confluent in a frond). 



* Elaters and columella wanting. 



1. RICCIA. Capsule valveless, globular immersed in the frond Involucre none. 



2. SPELEROCARPUS. Capsule valveless, globular, sessile on the frond. Involucre sessile. 



* * Elaters none, or imperfect : columella present. 

 8. ANTHOCEROS. Capsule 2-valved, elongated linear, pedicelled. 



4. NOTOTHYLAS. Capsule 2-valved half-way down, sessile on the frond. 



# # * Elaters with 1 or 2 spiral fibres : columella none, 

 -i- Capsule opening irregularly, nearly sessile. Fertile receptacle peduncled. 



5. MARCHANT1A. Fertile receptacle 8- 10-rayed. 



6. PREISSIA. Fertile receptacle 4 - 5 ribbed 



7. DUMORTIERA. Fertile receptacle convex, hairy. 



8. FEGATELLA. Fertile receptacle conical. 



9. REBOUXJA. Fertile receptacle hemispherical, 4-5 lobed ; the lobes acute. 



10 GRIMALDIA. Fertile receptacle conical-hemispherical, 4-5 lobed ; the lobes truncate. 

 11. FIMBRIARIA Fertile receptacle conical, tuberculate : involucre fringed. 



12 PLAGIOCHASMA. Fertile receptacle minute, 2-4 lobed, concealed by the ascending in- 



volucres. 



- -i- Capsule opening regularly by 4 valves, pedicelled. 



13 METZGERIA. Frond with a midrib, which bears the fruit on its lower surface. 



* By WILLIAM S. SULLIVANT, Esq. 



