EQUISETACE^. 169 



and then solitary or in pairs, resembling the stem in miniature, with 

 the first internode much shorter than the stem-sheath, below which it 

 is produced ; sheath enclosing the first internode of the branch, 

 pitchy-black, shining, irregularly toothed ; sheath at the apex of the 

 first and succeeding internodes of the branch terminated by ovate- 

 triangular apiculate pitchy-black teeth without furrows on the 

 back ; the succeeding ones similar to those on the main stem. Spike 

 oblong- or oval-ovoid, abruptly acuminated and mucronate, pitchy- 

 black, its base usually embraced by the teeth of the uppermost stem- 

 sheath. 



Var. a. genuinum. 

 Plate 1897. 

 E. variegatum, var. arenarium, Newm. Bab. Man. Brit. Bot. ed. viii. p. 451. 



Stem usually slender, often very slender, flexuous, decumbent or 

 prostrate ; stem ridges each with 2 acute angles, and a conspicuous 

 central furrow. 



Var. /3. majus. 



Stem rather slender, not flexuous, erect; stem ridges each with 

 2 acute angles and a conspicuous central furrow. 



Yar. y. Wilsoni. Newm. 

 Plate 1898. 



Stem stout, not flexuous, erect, stem ridges with 2 obtuse angles 

 and a shallow central furrow, less rough than in vars. a and ft. 



Yar. a in damp places on sandhills, and on damp rocks and 

 by the sides of streams. Rare. Salcombe cliff, near Sidmouth, 

 Devon ; reported from Somerset and Flint ; plentiful on the sand- 

 hills at the mouth of the Mersey, as at Wallasey and New Brighton, 

 Cheshire, and at Bootle, Crosby and Southport, Lancashire ; near 

 Settle, Yorkshire ; Teesdale ; in several places by the river Trthing, 

 near Wardrew, Northumberland, and by the same river above the 

 upper stepping-stones at Grilsland, Cumberland. In Scotland it is 

 reported from the Clyde Islands (Prof. Balfour, Top. Bot.); Frank- 

 field Loch, Lanark ; North Berwick, Haddington ; near Largo and 

 Tentsmuir, Fife (Mr. C. Howie) ; sands of Barry, Forfarshire ; banks 

 of the Dee, Kincardineshire ; near Tain, Ross-shire. In Ireland it 

 is found on sandhills at Port Marnoch and Port Crane, Dublin ; 



VOL. XII. z 



