I.— NOTES ON THE NOMENCLATURE OF 

 BRITISH MOSSES. 



By Mr JOHN WALCOT, President. 

 (Read Oct. 27, 1882.) 



The Moss plant, in its perfect state, consists of roots, stem, leaves, 

 fruit-stalk, and seed-vessel. These parts vary more or less in size, 

 colour, shape, and condition ; and the earnest student must make 

 himself familiar with all these varieties, if he would make any real 

 progress in the knowledge of Moss life. Several distinct pecu- 

 liarities mark off the Moss plant from other parts of the vegetable 

 kingdom. Its leaves have no footstalk, and are attached at their 

 lower edge to the stem ; some of them are serrated at the margin, 

 but none of them are divided and compound, as those of many other 

 plants are. Their surface is free from everything like hairiness ; 

 they do not decay and fall oif from the stem, and, as a result of this 

 enduring character, do not remind us of our frailty and destiny as 

 do the falling leaves of other plants, for they may be kept for 

 months, and even years, and retain the power of reviving when 

 placed in water. 



In the early stage of his studies, the student's attention will be 

 sure to be arrested by the singular fact that the slender stem, 

 called the seta, on the summit of which the seed-vessel rests, in 

 some Mosses projects from the summit of the plant, and in others 

 from the side of it. This distinct peculiarity has very properly 

 been fixed upon as the first means of division. All Mosses are 

 classed under the terms Acrocarpi and Pleurocarpi, — the one ac- 

 curately describing fruit from the summit, the other fruit from the 

 side. In later synopses a third term, Cladocarpi, has been adopted 

 to describe some plants whose fruit-stalk, being on short lateral 

 branches, appears to be lateral, thougli in reality it is terminal. 

 The capsule, or seed-vessel, of the Moss plant, as a rule, 

 possesses a small lid called the operculum, a beautiful fringe 

 about the mouth called the peristome, and a thin covering or 

 veil over the upper part of it which is called the calyiitra. In 

 Moss life, as well as in other things, this general rule has its ex- 

 ceptions. A few Mosses have no operculum ; a few others Jiave 

 no peristome, while of those which have it, in some the circle of 

 fringe is single, in others it is double. These exceptions have 

 been made the bases of other divisions which are as accurately 

 expressed as those which are based upon the position of the seta. 

 Hence in the progress of nomenclature we have the following : 



VOL. I. D 



