52 DICRANACE/E. 



often with special angular cells. In a very few cases the capsule 

 is more or less spherical, and cleistocarpous, with irregularly torn 

 calyptra; in all the other species the calyptra is smooth, narrow, 

 cucullate, very rarely mitriform, capsule on an elongated seta, 

 narrow, oval to cylindrical, frequently cernuous and gibbous; 

 peristome of 16 teeth, usually cleft above, sometimes to base, into 

 two lanceolate or subulate divisions, transversely articulated, with 

 fine vertical striae between the articulations, occasionally imperfect, 

 usually reddish, the interior plates usually thickest, often 

 transversely trabeculate. 



This constitutes a fairly natural family, though on one side 

 bordering closely on the Tortulaceae ; one or two of the genera, 

 as Ditrichum, might well, indeed, judged by the characters of 

 their fruit alone, be placed under that order, but the general 

 facies and leaf-form is that of Dicranaceas ; indeed in every case 

 in this order where the form of the fruit or the structure of the 

 peristome might appear to connect a species with the Tortulaceae 

 its true position will be rendered apparent either by the lid being 

 longly subulate or by the leaves being narrow and linear- 

 lanceolate or subulate, with narrow rectangular areolation. The 

 cleistocarpous species of this order are recognisable by the leaf- 

 cells in the upper part being small and narrow, and smooth, not 

 papillose. 



The student will at first, no doubt, have some difficulty in 

 referring some ambiguous species of both Tortulaceae and 

 Dicranaceae to their right Order, but the difficulty will soon dis- 

 appear when a little practical acquaintance has been gained with 

 the plants themselves. 



As many as 600 species have been described. The British 

 members of the Order may be classified under seven Tribes, 

 which, for the sake of convenience, are tabulated here. 



1. Ditricheas. Leaves lanceolate or lanceolate-subulate, 

 smooth, without distinct angular cells. Capsule rounded, cleisto- 

 carpous ; or ovate to cylindrical, either erect and symmetrical or 

 slightly inclined and unequal, smooth ; lid conical ; peristome 

 teeth 16, very narrow, forked or cleft to base into 32 filiform divi- 

 sions. 



2. Seligeriea;. Plants minute. Leaves lanceolate-subu- 

 late, smooth, without distinct angular cells (in the British species). 

 Peristome of 16 short teeth, cleft or perforated, or entire, some- 

 times wanting. Capsule erect or nearly so, equal, smooth or very 

 slightly and irregularly striate. Lid rostellate or shortly subu- 

 late-rostrate. 



