BRYACE^.] 160 [Bryum. 



in the keel and i 3 intermediate filiform cilia, generally transversely 

 appendiculate, rarely abortive. Growing on the ground, rocks and 

 walls, rarely on tree trunks. Der. fipvov a moss. 



The genus Bryum comprises some 400 species, varying in size, but in 

 most cases closely allied in habit and by the form of their beautiful pear- 

 shaped capsules. The leaves in many approximate so closely in form and 

 structure, that in a sterile condition it is hardly possible to determine the 

 species with certainty, as the nature of the endostome and relation of the 

 reproductive organs must be clearly made out. The former is best attained 

 by soaking the capsule, cutting off the peristome and laying it flat in water 

 between two slides. 



The formation of the endostome has been used to characterise some 

 other sections of the genus, thus in Brachymenium, it is reduced to a simple 

 erose membrane about half as high as the teeth, and in Acidodontium the 

 processes are cleft into two divergent segments ; but after all these groups are 

 purely artificial, and though most useful in hunting up species, they often 

 separate far apart some which are closely allied, e.g., B.fallax and B. pattens. 

 Again, we may notice a close relationship among certain species and yet be 

 quite unable to define it in words, as in B. argenteum, bicolor, erythrocarpum, 

 murale, marginatum, Mildei, &c., or in B. lacustre, Marratii, turbinatum, calophyllum 

 and Warneum, and there is a capillare group, and most distinct of all that 

 marked by B. proliferum ; continued observation of the living plants in the 

 field of Nature may eventually clear away some of the difficulties which at 

 present beset our path. 



CLAVIS TO THE SPECIES. 



Sect. i. SCLERODONTIUM. Shoots filiform, julaceous with 

 appressed coriaceous leaves, the upper cells linear. 



Leaves obtuse, the nerve vanishing. filiforme. 

 pointed, nerved to apex. concinnatum. 



Sect. 2. CLADODIUM. Leaves erecto-patent. Endostome adhering 

 to peristome, cilia abortive. 



Nerve vanishing. 



Capsule subglobose, leaves obtuse. Marratii. 



oblong, leaves pointed. calophyllum. 



Leaves short.pointed, nerve reaching apex. 



Not limbate. lacustre. 



Limbate. 



Synoicous, caps, pale on a short seta. purpurasccns. 



Dioicous, caps, brown on a long seta. fallax. 



gradually acuminate with long points. 



Not limbate. Warneum. 



Limbate. 



Caps, prominent on the back, mouth oblique. cernunm. 



regular, nerve longly excurrent. 



Caps, narrowly pyriform, long-necked. inclinatum. 

 ventricose in middle, short-necked. pendulum. 



