52 parsons' moss flora of the east riding. 



heathy firwoods on the alluvial sand of the Vale of York. The 

 former tract yields some of the mosses characteristic of hard 

 calcareous strata, e.g. Neckera crispa, Ditrichum flexicaiile and 

 Eficalypta streptocarpa ;'^ the mud-capped stone walls are favorite 

 habitats for the minute annual species, as Pottia ; and the tree 

 trunks are covered to a greater extent than in other parts of the 

 district with corticolous mosses and lichens, among which Cijphcea 

 heteroiiialla., a southern form, may be mentioned. 



The wet sandy heaths of the Vale of York abound with the 

 larger terrestrial and bog-loving mosses, e.g. species of Sphagnum, 

 Dicranum, Polytrichum and Hypnwn, which in moist shady 

 situations attain a considerable degree of luxuriance; some of the 

 less frequently fertile Hypnacece, as H. Schreberi, If. spleiide?is and 

 H. triquetriDii being occasionally found in that state. Although so 

 little elevated above the sea level it is on these wet moors if any- 

 where that we must look for any species approaching a northern or 

 mountain type; the rare Dicranum spurium, Breutelia arcuata 

 and Tetraplodon angiistatus, recorded many years ago, may be 

 considered to belong to this type, but the Racomitria so abundant 

 and characteristic of hilly regions are conspicuous by their absence. 

 R. canescens however occurs on Strensall Common in the adjacent 

 part of the North Riding, and also on sandy heaths in Lincolnshire, 

 just across the Humber, so that it is very probable that diligent 

 search may yet discover it in the East Riding, especially as certain 

 mountain Lichens, e-g. Platysma glaiicurn, Cet?-aTia acideata and 

 islandica, and Cladonia uncialis occur on the sandy heaths of the 

 East Riding. 



It may be remarked that with a few exceptions, as the 

 Polytricha, Orthotricha, Plagiotheciuin denticulatum, Hypfiiivi 

 cuspidatum, H. paliistre, Tortilla convoluta, &c., the mosses of this 

 as of other lowland districts perfect their fruit in the winter and 

 spring. The mosses of alpine regions, on the other hand, many 

 of them ripen their fruit in the summer. 



* Anomodon vlticulosics should be looked for in this part of the Riding. 



Trans.Y.N.U., 1878. Series E 



