486 A. HESSELHO 



Note. Bryum tiirbimitnm is recorded from Iceland by M6rch r 

 Hornemann and Gronlund, but all the specimens in the collections 

 are wrongly determined. 



160. Bryum ventricosum Dicks. 

 Verv common 



\j 



One of the most frequent mosses, which occurs in numerous forms 

 everywhere on a damp substratum, both on soil and on rocks. In 

 water, for instance in moss bogs and along the banks of streams, it 

 forms extensive, light green mats. The plants are only slightly tomentose, 

 with large, spreading leaves, and thin- walled cells. In bogs, where it 

 occurs everywhere in abundance, it is sometimes low in growth, some- 

 times as much as 67 cm. high, and often richly fruiting. Forms from 

 a more dry substratum, for instance from rocky clefts, are low in growth 

 and densely tomentose. It is common upwards of 600 metres above 

 sea-level. 



161. Bryum arcticum (R. Br.) Br. eur. 



This species is widely distributed over the whole of Iceland, but 

 occurs, as a rule, rather sparingly. 



It grows on peat, on damp sandy soil and on humus-covered rocks, 

 usually mixed with other Brya, and hardly ascends higher than 200- 

 300 metres. The fruit ripens at the end of July. 



It varies rather considerably. The capsule is sometimes short and 

 inflated, sometimes more slender. The spores vary from 0.020 0.035 mm. 

 The lamellae are usually connected by one or two transverse bars* 

 Near Seydisfjordur a form has been collected with a partly aulacodont 

 peristome and very few transverse bars. 



162. Bryum pendulum (Hornsch.) Schimp. 



N. Iceland: Hof (O. D.)!. W. Iceland: Reykjavik!; Reykholtdalur!. 

 S. Iceland: Gilfoss (F.) ! ; Barkarstadr!; Breidabolstadr!. Vestmannaey !. In 

 previous lists some more habitats have been enumerated for this 

 species (Grl.; H. J.), but they are all due to confusion with other species, 

 mostly with B. arcticum. 



Bryum pendulum appears to be rather rare and, as a rule, has been 

 found only in small quantity mixed with other Bryum spp. on damp 

 sandy soil or on damp tuff rocks. Fruit ripens in the beginning of 

 August. 



As in Bnjiim iiiclinatum the base of the peristome may be rather 

 differently developed. Thus, in a specimen from Breidabolstadr, a 

 rather large reddish-yellow thickening had been developed which could 

 be loosened from the mouth of the peristome together with the peristome 

 tooth belonging to it, as in the species of Hagen's Brya hcvmatostoma. 



One of the specimens from Hof, collected by O.Davidson, was 

 monoicous, but was otherwise quite typical. 



