344 Transactions. — Bo tany. 



the wind'; while in some species of Gymnostomum, as well as in Calomnion, a 

 further provision is made by the walls of the capsule being much thickened at 

 the mouth, which reduces the size of the opening. In most of those genera in 

 which the apparatus for protecting the spores is more perfect this annulus falls 

 away* after it has performed its office of throwing off the operculum from the 

 capsule, but in the genera just mentioned it is persistent. t 



In (Enectangium also the spores are very minute and numerous, which gives 

 evident facilities for their far and wide dispersion! 



2. Mosses in which the peristome is used. 

 I come now to that large division of mosses which have a series of teeth, 

 called the peristome, arranged round the mouth of the capsule. In its most 

 complete state this peristome consists of an external row of sixteen conical 

 teeth, and an internal folded membrane divided above into processes sometimes 

 with cilia between each (fig. 7) . The inner peristome is, however, variously 

 modified, and is often altogether absent. The outer peristome consists 

 normally of sixteen teeth, which are sometimes split half way down, as in 

 Dicranum, Fissidens, etc. Sometimes they are divided to the base so as to 

 make their number thirty-two, as in Trichostomum and Tortula. In rare 

 cases also two teeth are joined together so as to reduce their number to eight, 

 as in the tropical genus Octoblcplmrum, while occasionally they are reduced to 

 four, as in Tetraphis. 



The peristome also is very variously developed in different mosses. In 

 some, such as Weissia, Didymodon, Conomitrium, etc., the teeth are short and 

 fragile and soon break off. In Trichostomum, Encalypta, etc., they are 

 stronger ; while in most genera they are strong and answer admirably their 

 purpose of preventing the too easy escape of the spores. 



These mosses can be divided into five groups in each of which the peristome 

 is used in a different way. 



(a.) The first group, which is represented in New Zealand by the genera 

 Dicranum, Dicranodontium, Campylopus, Jiacomitrium,\\ Leucobryum, Grimmia, 

 Ceratodon, Conostomum, and Symblepharis, have the peristome long and well 

 formed, and the teeth stand nearly erect round the mouth of the capsule with 



Symblepharis is an exception. 



it olnZ a it y fJ? U3 "^ « *? $**& here ' for its P eri 8tome being shorter than the annulus, 

 it cannot in any way affect the dispersion of the spores. 



r a riti I i a ?^i h ° W wt r ' b ? en able to trace ^y connection between the abundance or 



awrlJlZJZ^ £ ft f 2 * ° f lts 9 K>rea - For stance, the spores of Hypnum 



and R f Z%rtu™ LTt^ *" ^K twice the ^ mGteT of those °* * prutingum 

 and H. confertum, whde H. tnquetrum and //. purum hold an intermediate position. 



but Lect^anTSH/ ?ICMZar !i h \ teeth are ^y hygroscopic, spreading when dry, 

 ™J™* f„ Q i . Sh 3 htl y "icurved when wet. I have noticed that in species a sticky 



found am 



tween thp W+Ti »rwi w+C- — ~i— --> mxx^u. i» uxawn out into lines like 



pTp^^r eth ' *** by thls means thQ 8 P<>rea are often stuck on to the inn 



peristome 



