SPHAGNUM. 23 



mixed with a few hyaline ones, some of which are destitute of fibres ; in other leaves 

 the whole tissue is composed of chlorophyllose cells, arranged in a lax network. I 

 have gathered this form, or one very closely approaching it, on Ben Lawers. 



The long flat leaves of S. cuspidatum, undulated at margin, are sufficient to dis- 

 tinguish it from all others of the Acutifolia section, except S. intermedium, which 

 differs in the characters given above. 



SUB-OLASS II. ANDREiEALES. 



Spores and Columella developed from the Endothecium, the 

 Columella not penetrating the spore-bearing layer. Spore-sac 

 not separated from the wall of the capsule by any air-cavity. 

 Capsule opening by longitudinal slits. 



Order II. ANDRE^ACE/E. 



Mosses with something the habit of Grimmia, in small 

 compact cushions or more rarely in laxer tufts ; growing on rocks ; 

 of a dark reddish or purplish colour ; stems slender, rooting only 

 at the base, very fragile when dry, dichotomous, with fasciculate 

 branches. Leaves usuallycrowded, small, erecto-patent or falcato- 

 secund, of rather thick texture, from bright orange to deep 

 reddish black, usually more or less papillose ; cells small, 

 incrassate, rectangular and often sinuose at base, small, rounded 

 or angular above. 



Flowers terminal ; fruit, as in Sphagnum, enclosed until ripe 

 in the perichaetium, then exserted on a pseudopodium by the 

 elongation of the vaginula ; calyptra membranaceous, irregularly 

 torn at the base. Capsule oval, without lid, splitting perpendicu- 

 larly into 4, rarely 6-8 valves, united at top and bottom. Columella 

 persistent. Spores smooth or lightly papillose. 



The leaves when viewed by transmitted light are usually of 

 a bright orange or reddish brown, but when seen by reflected 

 light, as in the field, and especially when dry, they appear of a 

 much duller and darker hue, not unfrequently appearing almost 

 black. It is only when quite young and half-developed that they 

 show any trace of chlorophyll. In leaf-structure there is a 

 certain resemblance to the Grimmiaceae, and they are by Lindberg 

 placed next to that order. 



There is, as in the Sphagnaceas, very little variation in the 

 fruit ; the specific characters have therefore to be drawn almost 

 entirely from the perichaetia and the leaves ; it is probably on 

 this account that there has been a tendency to found species on 

 somewhat slight and inadequate characters. 



