OF NORTHUMBERLAND AND DURHAM. 267 



of lofty crag and barren sandliill — slionld present any very great 

 luxuriance of oceanic vegetation. Most of the more delicate 

 species could find no abiding place on rocks so constantly lashed 

 by northern waves and blasted by eastern winds ; and we accord- 

 ingly find that when such plants do occur, they are for the 

 most part stunted, and greatly wanting in the grace and beauty 

 appertaining to them when grown under more favourable condi- 

 tions. There are, however, some amongst the smaller Rhodo- 

 sperms, which attain to considerable luxuriance. I may espe- 

 cially note Polysiplionia parasitica and P. hyssoides ; but these, 

 when well grown, are always found to have been washed up from 

 comparatively still water, where they have grown on corallines 

 or on the stems of larger weeds.* 



Our list will be found to include several strictly northern 

 species, w^hich appear to reach their southern limit, or nearly 

 so, on this coast. Among such may be mentioned Odontlialia 

 dentata, PhyllojjJwra Brodia^i, Ptilota plwnosa, and Callithamnion 

 Arbuscula. Some, or perhaps all of these, are occasionally to be 

 met with further south, but never, I believe, in any considerable 

 plenty or luxuriance. Even the small differences of latitude 

 observable on the Northumberland coast suffice to produce 

 marked changes in the character of its inhabitants. Thus speci- 

 mens of Odontlialia gathered on Holy Island, are often remark- 

 ably fine, while those found about Whitley and CuUercoats are 

 comparatively poor and stunted ; and with the exception of a few 

 specimens found M^ashed up at Marsden and Sunderland, I know 

 no instance of its occurrence on the Durham shore. Among 

 peculiarly northern plants, we must mention also Eutliora cristata, 



when the waves beat heavily at the other end of the beach, how the tide oozes in ahiiost 

 without a ripple amidst this Archipelago of stones. And here it is that many of the more 

 delicate Algae grow most luxuriantly. Polysiplionia parasitica, P. byssoicles, Nitophyllum 

 ocellatum, and Desmarestia viridis are to be found in profusion, and they attain here (I 

 believe) a much greater size than on any other part of our coast. 



* It is remarkable that the marine flora of the west coast of Britain is mnch more southern 

 in character than that of the east coast. On the Isles of Man and Arran, for instance, many 

 species are found which seem rightly to belong to more southern latitudes. Mr. Alder, in 

 the preface to his Catalogue' of the Northumberland and Durham MoUusca, notices the same 

 fact in connection with the Fauna. The diversity is doubtless dependent on the uninter- 

 rupted flow of the Gulf Stream along the west coast, the influence of which is counteracted 

 on our side of the island by the stronger cold currents from the north. 



