372 [Proc. B. N. F. C, 



mountains." Of the 137 Irish species, about 58 seem to have 

 been found by the late Dr David Moore, of Glasnevin, in the 

 north and East of Ireland, chiefly in the glens of Antrim. 40 

 species have been found by the writer in County Down, but no 

 doubt a more extended search would bring to light many more 

 species. Of these the most interesting are: — Gymnomitrium 

 obtusum^ Radula aqtcilegia, Lejeunia^ Mackaii, and ovata. A 

 description was then given of the most interesting genera and 

 species, and their life history and structure explained by the 

 aid of some coloured diagrams, which had been prepared to 

 illustrate the paper. The frondose section, containing the 

 liverworts and crystalworts, have no distinct stem and leaves, 

 but a frond or thallus, like the lichens. The crystalworts 

 mostly grow on fallow ground and damp clay banks, and are 

 lovely little objects, not more than a quarter of an inch across, 

 especially the common Riccia glauca^ when the sun is shining 

 on it, and it glitters like a miniature ice plant. One or two of 

 them are to be found floating like the duckweeds on still ditches 

 and ponds. Everyone must be well acquainted with the com- 

 mon liverwort, Marchantia polymorpha^ which may be found 

 creeping over the pots in greenhouses, on damp banks, garden 

 walks, and courtyards. It holds firmly the doctrine of *' fixity 

 of tenure," and, moreover, believes that it has a " natural right" 

 to creep over and occupy every damp pot in the greenhouse, 

 with or without the leave of the present occupier. The fruit is 

 borne on the top of stalked receptacles, which may be seen 

 springing up out of the fronds in the month of July. But 

 neither hepaticae nor mosses are dependent upon any single 

 means for the increase of their species. They usually grow in 

 tufts or colonies, containing many individuals, and cover over 

 a large extent of ground in a short time. Provision has been 

 made in several ways to supply this constant demand for new 

 individuals. The old stem or frond may die in the centre, 

 and the outside branches become new plants. Sometimes cells 

 simply break off from the margins of the leaves of the mother 

 plant, and found new colonies. Sometimes a whole leaf or set 

 of leaves will do the same. Sometimes, when the plant has 



