Moore — On the Mosses of Ireland. 
331 
this department of our flora, by collecting from the scattered papers 
those species which are noticed in them as additions, along with 
several which I possess that are not yet published, and together with 
those in the old floras, referring each to its proper genus. In this 
way, I trust to offer to the Academy a full account of the Mosses of 
Ireland, so far as they are known up to the present time. 
The species described by the late Dr. Taylor in EloraHibernica," 
amount to 229, while those which have been added since the publica- 
tion of that work in 1836, up to the present time, are 140 species, 
these being rather more than one third of the mosses now known to be 
natives of Ireland. 
In the present essay I have endeavoured to arrange our Irish 
Mosses in Sub-orders and Tribes according to the latest knowledge of 
the subject, and in so doing I have followed, as being the simplest, 
and probably the best which has yet appeared, the plan adopted by 
Mr. Mitten in his Musci Austro-Americanip published in the Journal 
of the Linnean Society, vol. xii., 1869. 
Mr. Mitten's arrangement differs considerably from those employed 
by previous writers on the subject. In the flrst place, the two great 
divisions of Acrocarpi and Pleurocarpi which have been so long in use 
by Muscologists have been discontinued, and three other divisions sub- 
stituted, these being founded upon the structure of the peristome, 
which affords better defined characters than any other parts of the plant. 
Secondly, the group Cleistoearpi^ e. g. Phascum, &c., of authors, which 
have generally been considered to form a section separate from the 
operculate mosses, has been abolished as unnatural, and the species 
which composed it have been distributed among the tribes to which 
they have most natural affinity. 
In describing the genera and species, I have first given a brief 
diagnosis of each, and separately, the principal synonyms under 
which they have from time to time been designated by authors, fol- 
lowed by the habitats of the rarer kinds, and notices of their distribu- 
tion through Ireland, as far as I have been able to ascertain it. 
SUB-OEDERS AND TRIBES. 
Sub-order I. Stegocarpi. Capsule opening by transverse separation 
at the medial line; upper portion caducous, rarely persistent. 
HoMODiCTYi. Leaves composed of cells uniform in structure. 
1. Elasmodontes. Peristome of the capsule, with four narrow 
teeth composed of confluent membranous cells. 
Tribe 1. Tetbaphide^. 
2. Arthrodontes, Peristome of the capsule with 8 teeth in pairs ; 
16-32-64, variously cleft, and composed of a double stratum 
