THE BRYOPHYTA OF ICELAND 527 



to a very long and slender point, and are about 1 mm. long and 0.4 mm. 

 broad. The branch leaves are lanceolate and toothed along their entire 

 margin, with short nerve. The cells at the base of the leaf are quadrate, 

 yellow and rather thick-walled, 0.012 0.015 mm. broad; those in the 

 upper half of the leaf narrowly prosenchymatous, 0.08 mm. broad, and 

 68 times as long, and often somewhat wavy. 



278. Subsp. * Amblystegium littorale (C. Jens.) Hesselbo. 

 Syn. Amblyste.giiim serpeus var. liltoralis C. Jens, in "Faeroernes Mosser ". 



N. Iceland: Grimsey (0. D.)!. W. Iceland: Reykjavik!; Brjanslaekur 

 (H. J.)!. 



Both the plants agreed exactly with the specimens collected by 

 C.Jensen in the Faeroes. A. littorale, which is a Sub-arctic-Arctic form, 

 is probably widely distributed. It has been found not only in the 

 Fseroes and in Iceland but also on Jan Mayen (Dusen) and in Sweden, 

 on Gislo near Trosa (Arnell). It has as yet been found sterile only. 



279. Amblystegium compactum (G. M.) Br. eur. 



Vestmannaey (H. J.;!). SW. Iceland: Ondverdarnes, in a well toge- 

 ther with Trentepohlia aurea (H. J.)!. 



On Vestmannaey this species occurred rather frequently on the sides 

 of clefts and caves in tuff rocks. It grew there in company with 

 Trentepohlia, especially in places where water was percolating through, 

 and occurred sometimes in compact cushions several cm. deep, some- 

 times as a thin covering. The Iceland specimens agree exactly with 

 North American plants of A. compactum: occasionally, however, the 

 leaves especially of the forms growing as thin coverings are somewhat 

 broader, with shorter cells. 



W. Monkemeyer and L. Loeske (Revision einiger Amblystegien 

 aus dem Herbare Limpricht; Ungarischen bot. Blatter, 1911, p. 273) refer 

 Amblystegium salinnm Bryhn to A. compactum as var. salinuin (Bryhn 

 Mkm. On investigating numerous specimens of A. saliuum I have, how- 

 ever, arrived at the conclusion that these two species are in no way 

 connected with each other. Amblystegium compactum forms compact, 

 dark-green tufts with a somewhat silky lustre, closely interwoven in the 

 interior with rust} 7 brown rhizomes which proceed partly from the stem 

 and partly, in very great numbers, from the under side of the stem- 

 leaves. The stem is prostrate with apex rising upward, and with 

 numerous branches. The leaves are very close-set, longly decurrent. 

 erectly spreading and secund. The stem leaves taper from a broadly 

 ovate base to a long and slender point with strongly curved back apex. 

 The branch leaves are narrowly lanceolate, often with apex curved. 

 The leaf-margin is sharply toothed along its entire length, and especially 

 the lowermost teeth are often turned outwards or towards the base. 

 In the branch leaves the nerve reaches to the apex and is of almost 

 equal width along its entire length, straight, or sometimes slightly sinuous. 

 The leaf-cells are narrower than in any other Amblyslef/ium, 0.005- 



