(30) 



by spiral threads called claters. The favorite habitat of 

 hepatics is wet places, and mountains continually steeped in 

 clouds yield a surprising variety of forms. Closely related 

 to the hepatics is the group Anthocerotes ; these plants may 

 however be distinguished by the presence of a central axis or 

 column (columella) in the capsule, and there are several 

 other important structural differences in their tissues. 



The mosses (cases 41 to 48) follow the hepatics in order of 

 development and complexity ; they differ from them, however, 

 in many respects. The stem and leaves have more differen- 

 tiated tissues, and the leaves usually have a midvein. The 

 moss capsule generally opens by a lid under which there are 

 commonly appendages to aid in scattering the spores, which 

 in this case are not accompanied by spiral threads as they are 

 in the hepatics. The mosses fall into three primary groups : 

 First the "peat-mosses" {S-phagnuni) which differ from the 

 rest of the mosses in the development of the tissue-structure 

 of the capsule, and the spores ; they grow in swamps and 

 other wet places, and their accumulation forms peat. The 

 "black mosses" {Andreaea) differ from both of the other 

 groups in the valvular capsule ; they grow on dry rocks. 

 The true mosses vary exceedingly in size and aspect. An 

 examination of the specimens in the exhibition cases will 

 convey to the mind a better idea of this group than a descrip- 

 tion. They grow under all kinds of conditions from dry 

 rocks to deep water. Many of the kinds grow on almost any 

 kind of rock, earth or bark of trees, while certain ones are 

 more particular as to their habitat. Some will thrive only on 

 limestone, which they often gradually disintegrate and parti- 

 ally preserve in the masses of closely set plants as a calcare- 

 ous tufa ; other species prefer ground that has recently been 

 burnt over, as species of Funaria and Le-ptobryum, while 

 others grow only on the bones of dead animals or in places 

 where animal refuse has accumulated. 



Next higher in the plant kingdom is the subkingdom Pteri- 

 dophyla, or ferns and fern-allies, the seedless plants with roots, 

 stems, leaves and woody tissue (cases 49 to 55). The ferns 



