ORTHOTRICHUM. 25T 



pale, usually without hairs. Peristome teeth more distinctly 

 marked with sinuose lines, lamellae at base more developed, some- 

 times reaching nearly to the middle of the teeth. 



Hab. Stones and walls, most frequently on those which are calcareous ; not 

 uncommon. Var. $ in similar situations, often on stones by streams, more rare. 

 Fruit summer. 



O. cupulatum differs from O. anomalum in the shorter, wider, almost barrel- 

 shaped capsule, much less exserted, and more urceolate when dry, as well as in other 

 points. O. rupestre, besides the distinguishing characters of its Section, has in the 

 dry state a darker, longer capsule, usually with only eight ribs, and almost always- 

 with an inner peristome. O. rivulare differs in the leaves, broader and more rounded 

 at the summit, the reflexed peristome, etc. The var. nudum is considered a separate 

 species by Venturi, but I can hardly see greater differences between it and the type 

 than between 0. anomalum and its var. saxatih. I am inclined to think, however, 

 that strictly speaking the var. nudum should form the type of the species, and the 

 more common form, with less highly developed peristome, the variety. 



The ribs are not unfrequently obscure, even the primary ones, and rarely reach 

 quite to the base of the capsule, which is almost always wide, paler, and with a rather 

 inflated appearance. 



C. AFFINIA. 



4. Orthotrichum Shawii Wils. (Tab. XXXV. B.). 



In small tufts, deep green, somewhat resembling a small form 

 of O. leiocarpum, but shorter, with shorter leaves, and rather 

 smaller areolation. Capsule immersed ; smooth or with very 

 indistinct traces of eight bands, close to the mouth, oval or oval- 

 oblong, quickly narrowing at the base into the seta. Peristome 

 single, of 1 6 teeth, revolute when dry and touching the wall of the 

 capsule with their tips. Autoicous. 



Hab. Ash trees, Kilkerran Castle, Ayrshire (Shaw). 



A very rare species, hardly known elsewhere in Europe except in a few localities 

 in Germany and Corsica. It differs from O. leiocarpum mainly in the capsule showing 

 some traces of bands, while from O. rupestre var. Franzonianum it differs in the 

 reflexed peristome ; the stomata, too, as far as I have been able to examine them, are 

 found in the lower half of the capsule, and the latter is almost smooth. It has been 

 suggested, with some plausibility, that it is a hybrid between 0. leiocarpum and 0. 

 rupestre. 



5. Orthotrichum leiocarpum B. & S. (O. striatum Hedw.,. 



Braithw. Br. M. Fl.) (Tab. XXXV. C). 



Tufts usually rather loose and irregular, sometimes more 

 dense, dull green. Leaves long, lanceolate, tapering to a some- 

 what acute apex, margins revolute ; cells distinct, quadrate- 

 rounded or elliptical, incrassate, papillose. Capsule immersed, 



