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rjQ REVUE BRYOLOGIQUE 



which are thus marked is of course subject to some 



^^ifTntodon and mo.t genera of ^^^Lc'^'^ceae these 

 lines are present to a greater or less extent m most of the 

 snecies although entirely lacking m some. In all the 

 spec es' Pi/&sia they kre lacking although this genus 

 Shows strong indications of a.close relationship wiih fh/p- 

 num In^W the genera the Hypnaceous peristome is dege- 

 nSing-Nhe outer teeth are less perfect and these Imes 

 when present are confined to a few basal fS^^^^, fr^" 

 oiientlY being apparent on the lower one or two on y The 

 ?nner peristome has changed even more, usually lack mg 

 cma and with the teeth much reduced. In Ciimaa^^^^^^^ 

 Fontinalaceac, the Neckeraceae, and allied groups these 



lines are entirely lacking. , . . ^f tv.ic «nrt 



It seems scarcely probable that a character of this sort 

 should be so widely present unless the plants possessing 

 it had a common ancestry. It is present in none ot the 

 acrocarpous mosses so far as known to me, and m no 

 pleurocarpous mosses that are not admittedly the nearest 

 relatives of the Hf/pnaceae, unless we except the Ftay- 

 qophullaceae wich have an almost perfect Hypnaceous 

 peristome but are usually put in a distinct gro«p. In 

 Climacium and the other groups mentioned as lacking 

 these lines the peristome is so complete m many species 

 that it can scarcely be called a degenerate Hypnaceous 



^^When^i't comes to an actual arrangement of the genera 

 in anv general plan of classification there are many ditti- 

 culties. As has already been suggested, the first and grea- 

 test is that we have no fossils to aid us in de ermming 

 what was the primitive form. It may weld be that there 

 were at least two separate lines of descent from the acro- 

 carpous mosses, one foreach of the great groups outhned 



above, with possibly a third for the /'«^/'^«^«^^«'L-,Li. 

 seems probable that Porotrirhum, Isothecmm, Ptejogo- 

 vium Lescurea, and possibly a few other genera form a 

 separate family, closely related both to the Lcskeaceac and 

 I^mmcear. Thuidivm, Claopodhnn^ and their nearest 

 allies are certainly more closely related to the ^/^P{*«^f^^ 

 than to the Lcskeaceac as they differ chiefly in having 

 papillose leaf cells, wich have certainly been developed 

 indeoendentlY in several very different groups of mosses , 

 Ihefa^e proLbly a later offshoot from the Hy.p.iaceous 

 stem than those of the Lcskeaceac having an m^Pertect 

 peristome. Climacium Ruthemcum has a sporophite that 

 is perfectly Hypnaceous excepting the lack of cdia, a noi 

 uncommon lack in that group. Climacium proper appears 



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