[ 22 ] 
III. 
A LIST OF IRISH CORALLINACEA. By T. JOHNSON, D.S8c., 
(Lond.), F.L.8., Professor of Botany, Royal College of Science, and 
Keeper of the Botanical Collections, Science and Art Museum, 
Dublin; and MISS R. HENSMAN. 
[Read Aprit 20; Received for Publication! NovemBer 26 ; 
Published January 4, 1899.] 
Tue Corallinaceze form a well-defined group of marine red alge, 
characterised by the presence of carbonate of lime, the plant-body 
having a pink, brittle, chalky, or even stony consistence. The 
group is represented on the coast of Ireland by the genera 
Schmitziella, Choreonema, Melobesia, Lithothamnion (including 
Lithophyllum), and Corallina (including Jania). 
Until fifty years ago these sea-weeds were regarded as animals 
associated with the corals, and known as Nullipores. 
Schmitziella has a peculiar habitat, growing in the thick cell- 
wall of a green alga, Cladophora pellucida, Kitz. Choreonema 
forms wartlike projections on the joints of various species of 
Corallina. Melobesia occurs as an epiphyte in colonies of usually 
minute thin discs on Zostera and various sea-weeds. 
Lithothamnion and Lithophyllum have a more or less stony 
aspect, unbranched, or with small warty, or clumsy-looking, or 
delicate, or even ribbon-like branches. Rockpools—floors and 
sides—are often completely covered with Lithothamnion species. 
Corallina is, in some of its species, very common and widely 
distributed. It has a jointed, branched plant-body. At one 
time several of the genera were supposed to be the early 
1The publication of this Paper was delayed in the hope that the nomenclature 
of the Corallinacez, on which discussion is proceeding, would haye become more 
stable. 
