68 Mosses from Pre-Carboniferous Rocks. 
here will bring Cylindrothectum concinnum, and on one scree 
facing west where Saxifraga oppositifolia grows, we get Trichos- 
tomum tortuosum var. fragilifolium; in vertical clefts of the 
limestones we can also find Mnium orthorrhynchum ; a Thuid- 
zum found on these dry places is the one previously reported 
by us from Ingleborough, T. Philiberti1; it has recently been 
classed as a variety and called var. pseudo-tamarisct. 
The mosses group themselves in fairly distinct associations, 
if we get a flat surface of siliceous rock at a low angle with slight 
moisture draining over it, we shall find usually Andreea Rothit 
var. falcata, A. crassinervium, A. petrophila, Rhacomitrium 
heterostichum, R. fasciculare, R. aciculare, Campylopus atro- 
virens, Bryum alpinum. 
The nerved Andreea is much the most frequent, the 
Rhacomitria vary according to the amount of moisture, 
fasiculare if fairly dry, aciculare if wet. The Campylopus and 
Bryum vary in appearance with the moisture, in the wet 
places the former has much shorter or almost lacks the hair- 
point, and the Bryuwm looses the rich crimson metallic sheen, 
passing into the green variety; very occasionally in these 
places we get the var. nigvo-viride of Trichostomum crispulum, 
and the var. acutifolium of Diphyscium foliosum ; the frequent 
Zygodon (Amphoridium) Mougeotii in similar situations is very 
different in appearance and handle, being black below in place 
of the light brown, and harsh to the touch. 
Another group is that of the Grimmias on the rocks facing 
south below Moughton. Here we get a type of moss which 
can stand a large amount of drying ; some experiments made 
by E. Irmscher and published in Jahrb. f. wiss. Bot. 50, pp. 
387-449, showed that G. apocarpa still had a quarter of its 
leaf cells living after drying in a dessicator for 128 weeks ; 
G. pulvinata showed a similar result after 60 weeks’ drying, 
wheras the mosses usually found in water were soon killed, 
Fontinalis only surviving five days’ treatment. The species 
found here include Grimmia apocarpa, G. funalis, G. pulvinata, 
G. subsquarrosa, G. doniana; G. funalis and subsquarrosa 
being far the most plentiful, some tufts of the latter have the 
gemme in perfect condition. They appear not to have been 
found in the British Isles in this state before. 
Our next group is the moss flora of scattered siliceous 
boulders. This is fairly regular, the main part being Rhacomi- 
trium heterostichum with a little R. fasciculare, and Grimma 
apocarpa, this being of the gracilis type ; if sufficient soil, we 
find Polytrichum piliferum and occasionally Hypnum cupresst- 
forme. On one or two out of a great number examined we 
found Hedwigia ciliata. 
In the following list the nomenclature adopted is that 
employed in the census catalogue of the British moss club, 
Naturalist, 
