Paksons : Flowerless Plants and theie Habitats. 51 



or human agency are sometimes the habitat of mountain mosses ; thus 

 o;i the gritstone coping of an old clough at Dykemarsh, near Thorne, 

 I have found several species of mosses which do not, to my knowledge, 

 grow elsewhere in the district, or at least within several miles — and two 

 at least of them {Racomitrium laying inos am and PtycJiomitrium polypJiyl- 

 lum) are of a decidedly mountain type, and, I suspect, have been 

 introduced with the stones from the high moors of the west of 

 Yorkshire . 



Generally speaking, the older geological strata and the hard igneous 

 and crystalline rocks are the most favourable to cryptogams. This is 

 well shown at Charnwood Forest, in Leicestershire — a tract a few miles 

 square, where the old slate and granite rocks rise to the surface in 

 the midst of the new red sandstone plain, forming hills with jagged 

 outline like mountains in miniature, though only 800 feet high ; 

 these yield an abundant cryptogamic flora, including many alpine 

 species. Dr. Lindsay says, however, that in Scotland comparatively 

 few lichens are found on the basalt rocks. I have not seen enough 

 of basalt rocks to confirm or disprove this statement, but on the 

 whinstone of Teesdale and the somewhat similar serpentine at the 

 Lizard lichens are very abundant.* In the district where I used to 

 live, where a great range of strata occurred within a small compass, 

 I noticed that the calcareous oolitic rocks yielded more mosses and 

 lichens than the chalk, and the carboniferous limestone than the 

 oolites. With sandy strata the rule does not appear to hold good ; 

 the old red sandstone did not in Somerset yield more than the upper 

 green sand ; and here the new red sandstone tracts are not nearly 

 so rich in cryptogams as the alluvial sandy heaths. 



The influence of the chemical composition of the soil upon 

 the terrestrial cryptogamic flora is quite as marked as upon the 

 flowering plants ; for instance, some kinds eschew lime, others 

 require it ; and an old thatched roof in a calcareous district, or a 

 limestone wall in a non-calcareous district, will often yield species 

 not found elsewhere in the neighbourhood. The classification of 

 soils which I believe to be best for botanical purposes, is — 1. Igneo- 

 metamorphic, as granite, slate, &c. ; 2. calcareous ; 3. clayey ; 

 4. sandy ; and 5. peaty, with intermediate varieties. Each of these 

 classes of soil is marked by the presence or absence of particular 

 species of cryptogamia ; but this is a wide subject, and I must leave 

 it for another occasion. 



* Those who have seen Mr. Brett's beautiful picture, "The Cornish Lions," in tke 

 Royal Academy Exhibition of 1878 will remember the rich orange colour of the 

 cliffs : due to the thick tapestry of orange lichen (Parmelia parietina) with which 

 they are covered. 



