352 FONTINALACE/E. 



* * Diplolepideas Pleurocarpas (v. ante, p. 232). 



Pleurocarpous mosses ; i.e., the fruit is produced from a 

 lateral bud on the side of the stem or branches, not at the apex. 

 Stems usually more or less prostrate, with the branching 

 frequently pinnate or sub-pinnate (branches frequently erect), 

 rarely dichotomous. 



[The seta in the pleurocarpous mosses may appear to be 

 terminal on a very short lateral branch, but this will be found on 

 examination to be only an elongation of the perichaetium, 

 originating in a lateral bud on the stem, containing the 

 archegonia ; the elongation taking place after fertilisation, and 

 belonging therefore to the sporophyte. The peristome is that of 

 the Diplolepideae, and in the majority of the genera and species 

 closely resembles that of the Bryaceae. 



It is a curious fact that throughout the pleurocarpous mosses 

 the inflorescence is almost always autoicous or dioicous, very 

 rarely, indeed exceptionally synoicous. 



The stem-leaves often differ in form and other characters 

 from those of the ultimate branches. In the following descrip- 

 tions, unless otherwise explained, the term leaves refers to those 

 of the secondary stems ; the primary stem being as a rule 

 inconspicuous, often leafless, or with only rudimentary leaves, so 

 that it may be termed stoloniform.] 



Order XIX. FONTINALACE^E. 



Aquatic, floating mosses, adhering only at the base ; usually 

 much elongated. Leaves in several rows or tristichous, nerveless 

 or single-nerved, cells rhomboid-hexagonal, or linear and sub- 

 vermicular, long, smooth. Capsule immersed or shortly exserted ; 

 annulus none. Calyptra cucullate or mitriform, glabrous. 

 Peristome of 16 outer teeth, transversely articulate and trabecu- 

 late on the inner face, and an inner peristome of 16 cilia, more or 

 less completely united with one another by transverse partitions 

 at regular intervals. 



A very distinct Order of mosses, known at once by their 

 aquatic habit, the areolation of their leaves at once distinguishing 

 them from Cinclidotus, and the hardly exserted or even immersed 

 capsules from the aquatic Hypneae. In the absence of fruit there 

 is indeed, a close resemblance between some of the Harpidioid 

 Hypneae and the species of Dichelyma, but the latter may usually 



