346 Transactions. — Botany. 



grow in forests and sheltered places. With the exception of some species of 

 Orthotrichum the capsule is always exserted, and in Macromitrium it is 

 sometimes much elongated. Fissidens is the only genus with the mouth of 

 the capsule inclined or directed downward. 



id.) In the fourth group the peristome is double, the inner one being 

 composed of a membrane more or less divided in the upper part. The outer 

 peristome is hygroscopic, closing tight over the mouth of the capsule when 

 moist, and spreading outward with the tips of the teeth incurved when dry. 

 The inner peristome is not hygroscopic, but on the opening of the outer 

 peristome the interior projections, or " trabeculje", as well as the points of the 

 teeth, get entangled in the perforations and cilia of the inner peristome and 

 drag it open, often quitting their hold with a jerk which spirts out the spores 

 to some little distance, thus answering the same purpose as the elaters of the 

 Hepaticce. This group is a very large one and includes the New Zealand 

 genera of Bryum, Cladomnion, Isotheciumj Hypnmn (fig. 7), Rhizogonium, 

 Hypopterygium, Racopilum, Hooheria, and others. These mosses are chiefly 

 inhabitants of plains and forests ; in nearly all the species the capsule is 

 inclined, while in some, e.g., Bryuni and Mnium^ it is pendulous (fig. 13), so 

 that its mouth is directed straight downward. All have the fruit-stalk 

 elongated except Fontinalis, a northern genus that lives in water. In this 

 moss (fig. G) the outer peristome is hygroscopic, and the inner is converted 

 into a conical membrane regularly perforated with square holes, which 

 prevents the spores being washed out too quickly. 



(e.) The fifth group consists of the genus Funaria alone, which stands 

 apart from all other mosses as far as the apparatus for the dispersion of the 

 spores is concerned. In this moss the peristome is double, the jDoints of the 

 teeth of the outer one being connected by a disc, which in time falls away. 

 The inner consists of narrow teeth, which might almost be called cilia. Both 

 are hygroscopic, and curl outward when dry after the rupture of the disc. The 

 capsule also is pendulous on a hygroscopic fruit-stalk, which, however, when 

 either curling or uncurling, always keeps the mouth of the capsule directed 

 downwards, and thus protects it from the rain. We thus see that this moss 

 combines the advantages of the first and third groups. At first its strong 

 united peristome enables it to distribute its spores in small quantities to high 

 winds only, while afterwards the mouth of the capsule opens wide, and 

 allows, on the first dry day, all those spores that still remain to be blown 

 away, and so prevents them from being wasted through failing to escape from 

 the capsule. This is perhaps the most perfect apparatus possessed by any 

 moss, and we cannot wonder at its almost cosmopolitan distribution. 

 3. Mosses in which the columella is used. 



These mosses may be divided into two groups, which use the columella in 

 connection with the operculum or the peristome respectively. 



