THE BRYOPHYTA OF ICELAND 525 



asplenioides, Pohlia cruda, etc., up to about 300 metres above sea-level. 

 Near Kolvidarhol and Seljaland it was found at an altitude of about 

 400 metres. Only sterile specimens have been found. 



270. Plagiothecium denticulatum (L.) Br. eur. 



X. Iceland: Myvatn (Grl.;!); Grimsey (O. D.)!; Hof (O. D.)!; Yidvik 

 (P. Sofoniasson)!; Asbyrgi!. NW. Iceland: Grunnavik!; Kaldalon!. \\ T . Ice- 

 land: Gilsbakki!; Hafnarfjordur!; Reykjavik!. S. Iceland: Thingvellirl; 

 Holt!: Vestmannaey!. 



Found here and there on humus-covered rocks or in lava-clefts, 

 but everywhere scantily only, and sterile. 



Recorded by Konig and Steenstrup from Iceland, but there are 

 no specimens of it in the collections. 



Plagiothecium undulatiim is recorded by Lindsay and P. silesiacum 

 by Hornemann from Geysir), but no specimens of either of these 

 two species are to be found in the collections, so the determinations 

 are undoubtedly erroneous. 



\j 



271. Plagiothecium pulchellum (Dicks.) Br. eur. 

 Isopterygium nitidum v. pulchellum Lindb. 



Iceland (Morch). Commonly distributed over the whole of Iceland. 



Grows in rock-crevices, caves, lava-clefts, etc.; either in small un- 

 mixed tufts or, more often, intermixed with other mosses. It does not 

 appear to ascend higher than about 400 metres above sea-level and. as 

 a rule, sets fruit. 



The majority of the plants which have been investigated belong to 

 the type. Yar. nitidiilnm Wahlb. L. et J. (Isopterygium nitidiilum Lindb.) 

 is far rarer, and growls by preference especially in deep shade; but, for 

 the rest, this form is not very characteristic and passes without limit 

 into the type. 



272. Plagiothecium depressum (Bruch) Dixon. 



S. Iceland: Holt!; Vestmannaey, Heljusdalur!. 



In Heljusdalur it grew in masses on a talus of fallen blocks and 

 debris (Urd), everywhere covering the ground between the large blocks 

 with its brightly shining mats. Near Holt it was found mixed with 



CJ / 



Brachythecium velalimim at the bottom of a tuff cave at an altitude of 

 about 300 metres. 



273. Plagiothecium elegans (Hook.) Sull. 

 Isopterygium elcgdiis Hook. Lindb. 



S. Iceland: Reykirdalur!, at an altitude of 260 metres. 



It was growing here on warm soil in the neighbourhood of a 

 sulphur spring, on the ground below a projecting block of rock, in 

 company with Diplopyllnm albicans and Pellia Xeesiana. 



