XL HEPATIC M. 939 



appendages along both margins of the frond (Targionia). But whatever their form, the receptacles 

 all agree in presenting a tissue with a mamillated surface, the inamillae corresponding to an ovoid anthe- 

 ridium immersed in their parenchyma, and communicating with the outside by a small canal which 

 abuts against the top of the mamilla. These antheridia contain minute cells which again contain anthe- 

 rozoids ; these differ from those of Fossonibronia in their minute size, the shortness of their body, and the 

 extreme tenuity of their vibrating hairs. 



The sporangia, like the antheridia, are immersed in a common receptacle (Marchantia) ; sometimes 

 this receptacle is conical (Fegatella) or hemispherical (Reboulia). In Lunularia, the vegetation of which 

 is identical with that of the preceding genera, the sporangia are tubular, four in number, arranged in a 

 cross at the top of the pedicel. In Jwngermannia the sporangia, at first ovoid or spherical, open when ripe 

 into four valves, bearing the elaters in the middle. The elaters are wanting in the tribe of Ricciece, and 

 are very rudimentary in Antliocerea , 



The spores vary in size and appearance; they are ovoid or spheroidal, smooth or granular, or 

 echinulate . 



TRIBE I. JUNGERM ANNIE JS. 



Leafless, or furnished with stem and leaves. Archegonia and antheridia 

 developed at the extremity of the stem. Sporangium furnished with elaters, deprived 

 of columella. 



PRINCIPAL GENERA. 

 1. Plants ivith Leaves. 



Jungermannia. Frullania. Geocalyx. Schisma. 



Gottschea. Sarcoscyphus. Tricholea. Sendtnera. 



Lophocolea. Calypogeia. Gymnomitrium. Pleuranthe. 



Lejeunia. Saccogyna. 



II. Plants ivithout Leaves. 



Pellia. Fossombronia. Aneura. Blasia. 



Blytia. Metzgeria. Symphyogyna. 



TRIBE II. MONOCLEE^}. 



Frond an irregular thallus or leafy stem. Sporangium solitary, opening length- 

 wise, deprived of columella, elaters carried away with the spores. 



GENERA. 

 Monoclea. Calobryum. 



TRIBE III. RICGIE^. 



Frond or thallus dichotomous, traversed by a median nerve. Archegonia and 

 antheridia immersed, or superficial and sessile. Sporangium without columella or 



elaters. 



PRINCIPAL GENERA. 



Riccia. Ricciella, Riellia. Oxymitra. Corsinia, Sphaerocarpus, 



