94 RECENT ADDITIONS TO OUR MOSS FLORA. 



The Homodictyi are separated into three subdivisions, according to 

 the structure of the peristome. 1. Elasmodontes ; teeth composed 

 of confluent cells — Tetraphidacea;. 'i. Nematodotdes : teeth composed 

 of filaments, sometimes free, usually combined into solid, tongue-shaped 

 processes as in Folytrichacea, or into a folded membrane as Buxbaumia. 

 3. Arthrodontes ; teeth transversely jointed, composed of a double 

 layer of cells, the outer of two rows of coloured ones, tlie inner of a 

 single series of hyaline cells ; an internal membranous peristome is 

 also often present. Here the Cleisfocarpous section is abolished, and 

 the species distributed among those families possessing kindred leaf- 

 structure. If we compare the old Phasciim serratnm, P. cuspidatum, 

 and P. suhulatiim, it is clear they have nothing in common save the 

 deficiency of a lid, which, after all, is a matter of development, for in 

 c)-ispnm and roslellatum the lid is perfectly distinct, though it does not 

 fall off, and there is thus a gradual transition to Gymnostomum micsv- 

 siotnum, G. tortile, etc. 



In enumerating the Mosses recently recorded as British, I shall en- 

 deavour to render the list more complete by the addition of synonyms 

 and descriptive characters, and I beg first to offer my sincere thanks 

 to the Rev. J. Fergusson, of New Pitsligo, and to Messrs. Hunt, of 

 Manchester, and Davies, of Brighton, for valuable information, and 

 specimens of rare species. 



Andre^ace.^. 



The close resemblance to one another among the species of the 

 genus Andreaa, has caused several to have been overlooked, but the 

 investigations of Zetterstedt, Tliedenius, and Schimper, have enabled 

 us to discriminate them, as well as to rectify their nomenclature. 



It may be a question whether some of the species are more than 

 varieties, especially when we see the endless forms assumed by A. 

 petrophila, nine of which having received names, I transcribe them 

 here, as probably most of them occur with us. Besides the British 

 species here tabulated, A. Hartmanni, A. Thedenii, A. spanifolia, and 

 A. Blyttil, are found in Norway and Lapland. 

 * Leaves nerveless. 



1. A. petrophila, Ehrhart — A. rupestris, Hed. : var. /8. acuminata ; 

 y. flaccida ; 8. squarrosula ; e. sylvieola ; t,. gracilis ; y. alpicola ; 

 3-. pygwcea ; t. robusla ; k. homonialla. 



