20I 



MOSSES, Etc., AT H0RTON=IN-RIBBLESDALE. 



C. A. CHEETHAM. 



HoRTON-iN-RiBBLESDALE is an excellent centre for a bryologist. 

 With such easy access to deep gills like Ling Gill, boggy swamps 

 as Swarth Moor, and a mountain with the variety of rock that 

 Pennyghent can offer, one has far more to do than can be 

 crammed into a day or even a week-end. The district has been 

 well worked, however, as the numerous records in our Flora, 

 and the lists on an excursion circular issued last autumn by 

 the Yorkshire Naturalists' Union show. In the present account 

 the nomenclature followed is that of the Census Catalogue of 

 British Mosses (1907). A short hour or so spent in Ling Gill 

 gives ample evidence of the possibilities of the place for mosses, 

 and one sees the more familiar forms as Thuidium tamaris- 

 cinum B. & S., Hylocomium triquetrum B. & S., H. loreum 

 B. & S., H. squarrosum B. & S., Hypnum commutatum Hedw., 

 but how different with their wavy fronds six to nine inches in 

 length. Then in dark crevices, Porotrichum alopecurum Mitt., 

 Mnium undulatum L., M. rostratum Schrad., M. punctatum L. 

 occur, of a size and growth that is scarcely associated with 

 mosses. Some leaves of M. punctatum L. were over quarter of 

 an inch in diameter. The striking features were Trichostomum 

 mutahile Bruch. in all the crevices with swelling patches of 

 Bartramia (Ederi Sw., and in shady ledges Orthothecium 

 intricatum B. & S., these three forming quite a feature of all 

 the damp perpendicular faces of the limestone. 



On Pennyghent this richness of growth was out of the ques- 

 tion. The difference of the vegetation on the limestone scars, 

 and the gritstone scars above them, was striking ; and was 

 even more apparent in the flowering plants ; the wealth of 

 Saxifraga oppositifolia, Sedum roseum, etc., is all gone when the 

 grits are reached, but on these grits we get Andrecea petrophila 

 Ehrh., and A. Rothii Web. & Mohr burnt up, dead looking 

 patches which will open out, however, on the first touch of 

 moisture, though now they crumble to dust when gathered. 

 The Rhacomitria prefer these grit rocks, and here we got 

 Rhacomiirium heterostichum var. gracilescens B. & S. although 

 Rhacomitrium lanuginosum Brid. seemed at home on the 

 limestone below. 



In Douk Gill on the way to Pennyghent, we got Plagiohryum 

 Zierii Lindb. Weber a elongata Schwoeg., and on a mass of tufa 



1908 June I. 



