HEPATICACEJE. 



[ 322 ] 



HERCOTHECA. 



the sporanges are formed on the under side 

 of these receptacles (fig. 223, p. 257, figs. 334, 

 337, 339), which are of varied forms, &c. The 

 sporanges on these either burst by valves 

 (fig. 335), or by circumscissile dehiscence 

 throw off a lid, as in Fimbriaria (fig. 339). 



The frondose forms do not all produce 

 elaters, and have not all the spiral fibres in 

 the cells of their walls. The exceptions are 

 the Riccieae, and the elaters of Anthoceros 

 are rudimentary. In Marchantia the elaters 

 are highly developed (PL 32. figs. 36, 37), 

 also the spiral tissue of the valves of the 

 capsules (PL 32. fig. 35). TARGIONIA has 

 branched elaters. 



The spores mostly have a double coat, but 

 not always (e. y. Marchantia) ; they germi- 

 nate by protruding a pouch-like process, 

 which becomes a filament, from which the 

 new fronds or leafy stems arise. 



The peculiarities of the different groups 

 above referred to will be better understood 

 after reading the following characters. 



Synopsis of the Families. 



A. Vegetation frondose, i. e. leaf and stem 

 confounded. 



1. ANTHOCEROTE^B. The vegetative 

 portion consists of a minute green membra- 

 nous or slightly fleshy body, growing on 

 damp ground, not exhibiting any distinct 

 mid-nerve; it is at once known by its peculiar 

 fruits or sporanges, consisting of slender 

 stalk-like bodies springing up irregularly 

 from the upper surface of the frond, which 

 forms little sheaths (vaginule) around their 

 bases. These stalk-like fruits burst when 

 ripe, splitting down the middle from the tip, 

 and display a central bristle-like column 

 (columella), to which adhere the minute hair- 

 like bodies (rudimentary elaters) which are 

 mingled with the spores. 



2. MARCHANTIE.E. The vegetative por- 

 tion is here also a succulent leaf-like expan- 

 sion, mostly exhibiting a more or less lobed 

 form, and without any conspicuous mid- 

 nerves in the lobes. The fruits are more 

 complicated structures than those of Antho- 

 ceroteae. From notches in the lobed frond 

 arise slender stalks terminating at the top in 

 an expanded structure (receptacle], resembling 

 in some cases a conical cap, in others a star 

 with a number of thick rays like the spokes 

 of a wheel, &c. The spores are formed in 

 membranous sacs attached on the under 

 surface of the cap or star-like body, and they 

 are accompanied by elaters of considerable 

 size exhibiting highly developed spiral bands. 



The sporanges have no columella, and burst 

 at the tip with more or less regular tooth- 

 like valves. 



3. RICCIE^I. Vegetative portion an ex- 

 ceedingly delicate cellular leaf-like structure, 

 more or less lobed, with an evident mid- 

 nerve. The sporanges are either imbedded 

 in the substance of the frond, or only ele- 

 vated on a very short stalk, and surrounded 

 by a membranous sheath derived from the 

 upper surface of the frond. The sporanges 

 have no columella and no elaters. 



4. PELLIE^E. Vegetative portion a leaf- 

 like frond, mostly with an evident mid-nerve, 

 from which arise the sporanges, consisting 

 of capsules, usually bursting by four valves, 

 more or less elevated on a thread-like stalk. 

 Sporange without a columella; spores ac- 

 companied by elaters. 



B. Vegetation foliaceous, i. e. leaves and 

 stem distinct. 



5. JUNGERMANNIE.E. Vegetative portion 

 a thread-like stem clothed with green mem- 

 branous leaves more or less overlapping at 

 their bases. Sporanges springing from the 

 end of the stem, raised on more or less 

 evident stalks, bursting by four valves and 

 spreading in the form of a cross; spores with 

 elaters, which often adhere to the valves of 

 the sporange. The leafy stem of Junger- 

 mannieae is generally readily distinguishable 

 from that of the Mosses by the peculiar 

 mode of insertion of the leaves which pro- 

 duces a peculiar flattened arrangement. 



BIBL. Hooker, British Jungermanniee, 

 1816 ; G. W. Bischoff, Bemerk. uh. die 

 Lebermoose, Nova Acta, xvii. p. 909. pi. 67- 

 71. 1835, Bemerk. zur Entwickl. der Leber- 

 moose, Bot. Zeit. xi. 113, Ann. des Sc. nat. 



3 ser. xx. 57 ; Lindenberg, Monographic 

 der Riccien, Nov. Acta, 1836, Synops. Hepa- 

 ticarum, 1844 ; Nees ab Esenbeck, Natur- 

 gesch. der Europ. Lebermoose, Berlin, 1836 ; 

 Ekart, Synopsis Jungermanniarum, Coburg, 

 1832 ; Greenland, Memoire sur le germination 

 de quelques Hepatiques, Ann. des Sc. nat. 



4 ser. i. 5; Hofmeister, Vcrgleich. Unter- 

 suchungen uber Kryptogamen, fyc., Leipsic, 

 1851. 



HERCOTHECA, Ehr. A genus of Dia- 

 tomaceae. 



Char. Frustules single, valves unequal, 

 turgid ; connecting membrane of the valves 

 continuous, not cellular, dividing beneath an 

 integument which is mostly veined, or 

 beneath free setae which occupy the place of 

 the integument and are persistent. Hence 



