46 Traitsactions of tJie [Sess. 



Astomi, without a mouth ; Gymnostomi, nated at the mouth ; and 

 Peristomi, with a fringe at the mouth. Under this last division 

 there are two others — Aploperistomi, with a single circle of fringe ; 

 and Diploperistomi, with a double circle. From such facts as 

 these, it is obvious that in the early stages of study it will be a 

 comparatively easy thing to assign Moss plants their proper position 

 in the system of nomenclature. With so many easily recognised 

 characteristics and clearly defined distinctions, the student may 

 arrange his treasures, and store them away in safety till he can 

 secure the time necessary for more minute examination, and for 

 endeavouring to discover the grounds of their generic and specific 

 names. 



In considering the origin of family and generic names, we soon 

 find out that they cannot be traced to any one part of the plant 

 exclusively. The generally accepted nomenclature can be traced 

 up to many sources. Some parts of the plant, as, for instance, the 

 organs of fructification, supply a greater number of names than 

 others ; but this honour does not belong to them alone. Modern 

 authors of distinction have done a great deal to change and modify 

 the names. They have designated some in a more scientific manner, 

 and have distributed one or two of the largest families under other 

 titles, but they have not abandoned the older titles altogether : 

 these are retained as the general designations, under which those 

 newly invented are arranged. Considerable differences exist in the 

 modern synopses, and at present it is impossible to say whether 

 any one of them will supersede the older arrangements and names. 

 The object aimed at in the present paper requires that we should 

 mainly refer to those names which have become familiar to us 

 through standard authors. This nomenclature proceeds along two 

 general lines, distinct from and unlike each other. 



I. One proceeds upon the acknowledged existence of some pecu- 

 liarity in the plant itself, — either in its habit, or nature, or organs of 

 fructification. HypnacefB, the largest family, derives its name from 

 a supposed natural property to induce sleep. It is probable that this 

 property consists rather in their soft and feathery character than in 

 any chemical virtue. If so, there are other Mosses that might claim 

 the same title with equal right. Why the one class has been 

 chosen and the other not, we cannot say ; but let no one complain 

 of this. The feathery Mosses afford an elysium of delight to the 

 eye and to the touch. On their down-like bed the most skeleton 

 forms of human life may rest in ease and comfort. The names of 

 some genera are taken from their habit of growth — as those called 

 Fontinalis, which grow in streams, and probably those called 

 Splachnum, which chiefly grow on the fa3ces of animals. Others 

 derive their names from a peculiarity of the fruit-bearing stalk 



