THE BOTANY OF ICELAND EDITED BY L. KOLDERUP ROSENVINGE PH. D. AND EUG. WARMING PH. D., SC. D. PART II 3. ERNST 0STRUP: MARINE DIATOMS FROM THE COASTS OF ICELAND. WITH ONE PLATE. 4. AUG. HESSELBO: THE BRYOPHYTA OF ICELAND. WITH 39 FIGURES IN THE TEXT. (PUBLISHED BY THE AID OF THE CARLSBERG FUND) COPENHAGEN J. FRIMODT LONDON JOHN WHELDON & CO. 1918 1 PRINTED BY H. H. THIELE. 3. MARINE DIATOMS FROM THE COASTS OF ICELAND BY ERNST 0STRUP WITH ONE PLATE The Botany of Iceland. II. 23 THE material used for this paper has been entrusted to me for examination by the Botanical Garden, Copenhagen. It embraces in all 438 samples collected by the following: cand. O. Davidsen (O. D.f), Dr. phil. Helgi Jonsson (H. Js.), Professor Chr. Gronlund (Grld.f), Mag. scient. R. Horring (H0r.), Inspector W. Lundbeck (Lb.), Dr. phil. C. H. Ostenfeld (C. H.O.), Dr. phil. O. Paulsen (O. P.) and Adjunkt B. Ssemundsson (B. S.).*) Dr. Thoroddsen has given me valuable assistance as regards the spelling of the names of the various localities, and has also shewn me the kindness to go through my list of names, without which my paper, in this respect, would scarcely have been in agreement with his work : The Botany of Iceland I , and for this assistance I tender him my hearty thanks. As regards the habitats given by the various collectors, I have specified these when a form appears in up to 3 samples, by adding the parts of the coast where it has been collected, as well as the name of the finder. In case a form is found in more than 3 samples, the number of samples and the parts of the coast are given only. As to the limitation of the diffe- rent parts of the coast, see Helgi Jonsson, the Botany of Iceland I, 1, page 6, and the map page 7. The samples are, according to the parts of the coast, apportioned as follows: South, given in the text as S 58 samples South-West ----- S.W 191 — North-West — - - — - N.W 30 — North — - - — - N 98 — East — - - — - E 53 — No locality - S. L. (sine loco) 8 Total 438 samples *) The letters in brackets affixed to the names of the collectors indicate the abbreviations of their names, as used in the text; a f signifies, that the person is by now deceased. 23* 348 ERNST 0STRUP! MARINE DIATOMS FROM THE COASTS OF ICELAND The names Europe, Africa, Asia, America, Australia, Greenland, Arctic Seas are abbreviated in the text respectively as follows : Eu., Afr., As., Am., Austr., GrL, A. S. Freshwater forms are frequently found in the samples examined from the coasts of Iceland; these are however excluded in this paper, but will be included in a future work dealing with the fresh-water diatoms of Iceland. On the other hand, several forms found in brackish water are here included. PENNAT^E Diraphideae Tropidoneis Cl. 1891. Cl. Syn., 1,22. Tropidoneis lepidoptera (Greg.) Cl. Cl. Syn., I, 25; V. H. Trt, Tab. V, fig. 287 (Amphiprora lep.). Stykkisholmur (S.W.), H. Js. Area: Ubiquist, A. S. Pleurosigma W. Sm. 1853. Cl. Syn. I, 32. Pleurosigma cuspidatum Cl. Cl. Syn. I, 35; Per. Pleur., Tab. V, fig. 16 (P. lanceolatum var. cusp.). Skalholtsvik (N.), H. Js. Area: Eur., Aust. Pleuposigma elongatum W. Sm. Cl. Syn. I, 38; V. H. Trt., Tab. VI, fig. 262. 7 samples (S.W. 4, N. 1, E. 2). Area: Ubiquist, Grl., A. S. Pleurosigma longum Cl. Cl. Syn. I, 38; Cl. & Gr. A. D., Tab. Ill, fig. 71. Sk6r5arstraumur (S.W.), H. Js. Area: Grl., A. S. Pleuposigma Nubecula W. Sm. Cl. Syn. I, 34 ; W. Sm. Syn., Tab. XXI, fig. 201. Skalholtsvik (N.), H. Js. Area: Eur., Afr., As., Am., Grl. Pleuposigma Stuxbergi Cl. & Grun. Cl. Syn. I, 41 ; Grim. Fz. J. L., Tab. L, fig. 56. Reykjavik (S.W.), H. Js. Area : Grl., A. S. 350 ERNST 0STRUP Caloneis Cl. 1894. Cl. Syn., I, 46. Caloneis brevis (Greg.) Cl. Cl. Syn. I, 61 ; V. H. Trt., Tab. IV, fig. 180 (Navicula br.). A5alvik (N.W.), Lb., Bu5ir (S.W.). H. Js. Area : Ubiquist, Grl., A. S. Caloneis brevis var. distoma Grun. forma latior, Cl. Syn, I.e.; Cl. & Gr. A. D., Tab. I, fig. 25 (Navicula brevis dist.). DyrafjorSur (N.W.), C. H. O. Area: As., A. S. Caloneis brevis var. vexans Grun. Cl. Syn., 1. c.; Tab. nost., fig. 1. Bu5ir (S.W.), H. Js. Area: Eur., As., A. S. I have given a drawing of this species, as it differs somewhat, by its very narrow apical and small central areas from the figures in A. S. N. S. D. tab. II, fig. 14 and fig. 14 in Per. Diat. mar. tab. X. I have not been able to see any punctuations of the striae, as shown in \r. H. Syn. tab. XI fig. 18; besides concerning this form see the remarks by Peragallo in D. mar. p. 81. Caloneis formosa (Greg.) Cl. Cl. Syn. I, 57 ; V. H. Trt., Tab. V, fig. 199 (Navicula form.). 4 samples (S.W. 3, N.W. 1). Area : Ubiquist, Grl. Caloneis Liber (W. Sin.) Cl. var. genuina Cl. Cl. Syn., I, 54. V. H. Trt., Tab. V, fig. 219. (Navicula L.). 8 samples (S.I, S.W. 4, N.W. 3). Area: Ubiquist, Grl., A. S. Caloneis Liber var. elongata Grun. Cl. Syn., I, 55. A. S. N. S. D., Tab. II, fig. 42 (Navicula elong.). Reykjavik (S.W.), B. S. Area: Eur.. Afr., As., Am., Grl., A. S. Caloneis Liber var. linearis Grun. Cl. Syn., I, 54; V. H. Trt., Tab. V, fig. 220. (Nav. L. lin.). 8 samples (S.W. 6, N.W. 1, N. 1). Area: Eur., Afr., As., Am. Diploneis Ehr. 1840. Cl. Syn., I, 76. Diploneis *stiva (Donk.) Cl. Cl. Syn., 1,94: A. S. Atl., Tab. VII, flg. 8. Eyrarbakki (S.W.) H. Js., DyrafjorSur (N.W.) C. H. O., Midhus(?) H. Js. Area : Eur., Afr., As., Am., A. S. MARINE DIATOMS FROM THE COASTS OF ICELAND 351 Diploneis bomboides A. S. var. media Grun. Gl. & Gr. A D., 41, Tab. Ill, fig. 54. Steinaklettar XS.W.) H.Js. Area: Eur., Grl., A. S. Diploneis chersonensis (Grun.) Cl. Gl. Syn., I, 91 ; V. H. Trt., Tab. XXVI, fig. 738. (Navicula chers.). 8 samples (S. 1, S.W. 5, N.W. 1, N. 1). Area: Ubiquist. In a sample Broddanes (N.) H. Js.) I have found a form, which agrees well with Navicula apis (see Per. Diat. mar., 121, tab. XIX, fig. 3—8) which b}' Cleve 1. c. is referred to Dipl. cherson. Diploneis coffaeiformis (A. S.) Cl. Cl. Syn., F, 81; A. S. N. S. D., Tab. I, fig. 22. Grjotnes (N.), C. H. O. Area: Eur., As., Am., Grl. Diploneis constricta (Grim.) Cl. Cl. Syn., I, 83; Donk. Br. D., Tab. VII, fig. 6. (Navicula Musca). IsafjorSur (N. W.), H.Js. Area: Eur., As., Am., Grl., A. S. Diploneis contigua (A. S.) Cl. var. Eadoxia A. S. Cl. Syn. , 1,83; Per. D. mar., Tab. XVII, fig. 6. (Navicula E.) Tab. nost., fig. 2. Vestmannaeyjar (S.), H. Js. Area: Eur., Afr., As., Am., A. S. I have given a drawing of this species, as the form found by me is somewhat more contracted in the middle than the figure shown by Peragallo. The other figures quoted by Cleve 1. c. have all approx- imately rectilinear sides. Diploneis Crabro (Ehr.) Cl. var. minuta Cl. Cl. Syn., 1,102: Per. D. mar., Tab. XV, fig. 7. Vestmannaeyjar (S.), H.Js., Reykjavik (S.W. , H.Js. Area: Eur., Aust. Diploneis didyma (Ehr.) Cl. Cl. Syn., 1,90; V. H. Trt., Tab. Ill, fig. 147. HofSi (N.), H.Js. Area: Ubiquist, Grl., A. S. Diploneis elliptica (Ktz.) Cl. var. grandis Grun. Cl. Syn., I, 92; Pant. Ung. Ill, Tab. XI, fig. 182 (Nav. praeclara). BuSir (S.W.), H.Js. Area: Eur. Diploneis fusca (Greg.) Cl. var. subrectangularis Cl. Cl. Syn., 1,93; A. S. At!., Tab. VII, fig. 4. Brokey (S.W.), H.Js., DyrafjorSur (N.W.), C. H. O. Area: Eur., As. 352 ERNST 0STRUP Diploneis incurvata (Greg.) Cl. Cl. Syn., I, 84; V.H.Trt., Tab. XXVI, fig. 733. (Navicula inc.). 22 samples (S. 1, S.W. 13, N.W. 3, N. 4, E. 1). Area: Eur., Afr., Am., A. S. Diploneis interrupta (Ktz.) Cl. Cl. Syn., 1,84; V.H.Trt., Tab. Ill, fig. 145. (Nav. int.). 13 samples (S. 7, N.W. 4, N. 1, E. 1). Area: Ubiquist, Grl., A. S. Diploneis lineata (Donk.) Cl. Cl. Syn., I, 85; V. H. Trt., Tab. XXVI, fig. 736. (Nav. lin.). Vestmannaeyjar (S.), H. Js., Reykjavik (S.W.), Grid. Area: Eur., Afr. Diploneis littoralis (Donk.) Cl. Cl. Syn., 1,94; A. S. Atl., Tab. VII, fig. 25. (Nav. litt.). Skogarnes (S.W.), H. Js. Area: Ubiquist, Grl., A. S. Diploneis major Cl. Cl. Syn., I, 96; V. H.Trt., Tab. IV, fig. 151. (Nav. Smithi). Vestmannaeyjar (S.), H. Js. Area: Ubiquist, Grl. Diploneis notata sp. nov., Tab. nost., fig. 3. Long: 41 yte, lat: 18 /*, str. 11 in 10^. Valva elliptica. Sulcis in medio leniter contractis. Linea api- cali, utroqve in latere costas in medio secante, praesente. Striis in sulcis absentibus, mediae in valva modo juxta nodulum centralem striae paucae abbreviataeqve adsunt. Vestmannayjar (S.), H. Js. Diploneis Smithi (Breb.) Cl. Cl. Syn., I, 96; Grim. Fz. J. L., Tab. I, fig. 41. (Nav. Sm. var. borealis f. minor.). 4 samples (S.W. 3, N. 1). Area: Ubiquist, Grl., A. S. Diploneis splendida (Greg.) Cl. Cl. Syn., I, 87; A. S. N. S. D., Tab. I, fig. 3 (Nav. subc.). Steinaklettar (S.W.), H. Js. Area : Ubiquist, Grl., A. S. Diploneis subcincta (A. S.) Cl. Cl. Syn., I, 86 ; V. H. Trt., Tab. XXVI, fig. 737 (Nav. subc,). 7. samples (S.W. 4, N.W. 2, N.I). Area: Eur., Afr., Am., Grl., A. S. MARINE DIATOMS FROM THE COASTS OF ICELAND 353 Diploneis? inaeqvalis sp. nov. Tab. nost., fig. 4. Long: 18 /«, lat: 7 /«. Valva elliptica. Striis uno in latere valvse 11 in 10 a, altero in latere 14 in 10/f. Dyrafjordur (N.W.), C. H. O. It is with great hesitation that I refer this small species to Diplo- neis. It seems closely allied to Navicula Reichardti Grun. var. Tschut- chschorum Cl. Cl. Syn. II, 65'; Cl. Vega, tab. XXXVII, fig. 48. Cleve places Nav. Reich, among »Naviculae lyratae«. fj *j In Diat. mar. p. 129 Peragallo places Nav. Reich, among Diploneis, but remarks as follows: »Cette espece n'est pas un vrai Diploneis, ma is ce n'est pas non plus une vraie lyree car il n'y a pas de stries entre les fourches on aires centrales et le raphe.« Naviculse Fusiformes Cl. 1894. Cl. Syn., I, 105. Navicula Acus Cl. Cl. Syn., 1,106; Per. D. mar., Tab. VIII, fig. 23. Reykjavik (S.W.), C. H. O. Area : Eur. Navicula fusiformis Grun. var. ostrearia Gaillon. Cl. Syn., 1,106; V. H. Trt., Tab. XXVII, fig. 769. 4 samples (S. 2, S.W. 2). Area: Eur., Grl. Navicula glabra sp. nov. Tab. nost., fig. 5. Long: 41 //, lat: 8 /«. Valva lanceolata. Raphe area augustissima cincta. Poris cen- tralibus raphes distinctis. Structuram ullam valvae perspicere non potui. Reykjavik (S.W.), H. Js. This species somewhat resembles the unnamed Navicula (from Hvid- ingso), delineated in A.S.N.S. D., tab. Ill, fig. 8, which in Cleve (Syn. I, 106) is found under the name of Nav. Schmidti, but Cleve, as well as Peragallo (Diat. mar. p. 67 give the number of striae as 17 in 10 //, consequently a distinct striation, while I have not been able to see any. By great en- largement however the valves assume the peculiar misty appearance, indicating a very fine structure. Naviculse Orthostichae Cleve 1894. Cl. Syn., I, 107. Navicula halophila Grun. Cl. Syn., I, 109; V. H. Trt., Tab. IV, fig. 191. (N. cuspidata v. hal.). Reykjavik (S.W.), C. H. O. Area: Eur. 354 ERiNST 0STRUP Navicula Kryokonites Cl. var.? islandica v. nov. Tab. nost., fig. 6. Long: 45^, lat: 8 /a. Valva anguste-lanceolata. Striis subtilissimis et, qvoad perspi- cere potui, subradiantibus, media in valva fasciam latam relin- qventibus. Brokey (S.W.), H. Js. It is with some hesitation I refer this form to Nav. Kryokonites Cl. It has no slight outward resemblance to Nav. Kryok. var. subprotracta Cl. (Cl. Syn. I, 109; Cl. Vega Exp., tab. XXXVII, fig. 46) and has also, in common with this, the fairly broad fascia; it differs partly by being somewhat larger, but especially by the very fine striae, which, as far as I could see, are slightly radiate. Nav. Kryok. subprotracta has 22 parallel striae, at right-angles to the raphe, in lO/i, and is found at Cape Ware- karema and off East-Greenland. Amphipleura Ktz. 1844. Cl. Syn., I, 125. Amphipleura rutilans Trentepohl. Cl. Syn., I, 126: V. H. Trt., Tab. V, fig. 255. (Berkeleya Dilhvynii An.). 6 samples (S.W. 2, N.\V. 2, N. 2). Area: Eur., Afr., As., Grl. Naviculae Mesolejae Cleve 1894. Cl. Syn., I, 127. Navicula3 mutica Ktz. forma Cohnii Hilse. Cl. Syn, 1,129: V. H. Trt., Tab. IV, fig. 167. (Nav. mut.). Vestmannaeyjar (S.), H. Js. Area : Ubiquist, A. S. Navicula (Dickeia) ulvacea Berk. Cl. Syn., I, 129; V. H. Trt., Tab. XXVII, fig. 781. Isafj6r5ur (N.W.), H. Js. Area: Eur. Naviculae Microstigmaticae Cl. 1894. Cl. Syn., 1,141. Naviculas (Schizonema) Grevillei Ag. Cl. Syn., I, 152: V. H. Trt., Tab. V, fig. 243. 24 samples (S.W. 19, N. 4, E. 1). Area : Eur., As., Am., Grl., A. S. In conformity with Cleve 1. c. I include under Nav. Grevillei the following: Schizonema apiculatnm Ag. V. H. Syn., Tab. XVI, figs. 4 — 8. Schizonema comoides Ag. V. H. Syn., 1. c. fig. 3. Navicnla Delognei H. V. H. V. H. Syn., Tab. XI, fig. 13. MARINE DIATOMS FROM THE COASTS OF ICELAND 355 Navicula Libellus Greg. Cl. Syn., I, 153; Donk. Br. D., Tab. IX, fig. 1. OndverSarnes (S.W.), H. Js., Flatey (S. W.), H. Js. Area: Eur., As. Navicula rhombica Greg. Cl. Syn., 1,152; Greg. T. M. S. IV, Tab. Y, fig. 1. 31 samples (S. 5, S.W. 20, N. 3, E. 3). Area: Eur., As., Grl. Navicula (Libellus) complanata Grun. var.? cnfr. Cl. Syn., 1, 153. 7. Tab. nost., fig. 7. Long: 56 /<, lat: 10 /*. Vah7a lanceolata, apicibus rotundatis. Raphe area hyalina an- gusta, in medio in areolam rotundatam dilatata, cincta. Striis me- dia in parte valvse segre modo perspiciendis, ibiqve 17 in 10/t, apices versus densioribus. BuSir (S.W.), H. Js. I consider this Navicula belonging to the form-series of N. complanata, perhaps most closely allied to N. compl. var. hyperborea Grun. (see Gr. Fz. J. L, tab. I, flg. 10) of which, as far as I know, no figure exists viewed from the valve-surface. Stauroneis Ehr. 1843. Cl. Syn., I, 144—151 (sub. Nav. Microst.). Stauroneis constricta (Ehr.?) W. Sm. CL Syn., 1,145; A. S. All., Tab. XXVI, figs. 35—39 (St. amphoroides). 4 samples (S.W. 1, N.W. 1, E. 2). Area: Eur., Am. Stauroneis Gregorii Balfs. Cl. Syn., I, 145; V. H. Trt., Tab. I, fig. 52. Bii5ir (S.W.), H. Js, Dyrafjor5ur (N.W.), C. H. O. Area: Eur., Am. Stauroneis salina W. Sm. Cl. Syn., I, 145; V. H. Trt., Tab. I, fig. 54. Olafsvik (S.W.), H. Js., Skalanes (E.), H. Js. Area: Eur., Afr., Am., Aust., Grl., A. S. Gomphonema Ag. 1824. Cl. Syn., I, 178. Gomphonema exiguum Ktz. Cl. Syn., 1,188; Heib. D. D., Tab. V, fig. 18. 91 samples (S. 15, S.W. 40, N.W. 10, N. 16, E. 10). Area: Eur, As, Grl. Gomphonema kamtschaticum Grun. Cl. Syn., I, 188; V. H. Syn., Tab. XXV, fig. 29. 28 samples (S. 4, S.W. 9, X.W. 3, N. 5, E. 7). Area : Grl, A. S. 356 ERNST 0STRUP Gomphonema kamtschaticum Grun. var. islandicum v. nov. Tab. nost., fig. 8. Long: 36 ^<, lat: 10 JLI. Str. minime 22 in 10 tu. Valva clavata, apice superior! rotundato. Raphe area hyalina angustissima, in medio in areolam parvam dilatata, cincta. Striis radiantibus, segre perspiciendis. Einarslon (S.W.\ H. Js., Grimsey (N.), O. D. Owing to its central area and the radiating striae, I consider this small species more likely allied to G. kamt. than to G exig. Trachyneis Cleve 1894. Cl. Syn., 1, 190. Trachyneis aspera (Ehr.) Cl. var. intermedia Grun. Cl. Syn., I, 192 ; A. S. Atl., Tab. XLVIII, fig. 14 (Nav. asp. int.). 19 samples (S.W. 11, N.W. 3, N. 4, E.I;. Area: Eur., Am., Grl., A. S. Trachyneis aspera (Ehr.) var. pnlchella Cl.Syn.1, 191 ; W. Sin. Donk. Br. D., Tab. X, fig. 1 (Nav. pulch.). 51 samples (S. 10, S.YV. 33, N.W. 3, N. 4, E.I). Area: Eur., Aust. Trachyneis Clepsydra (Donk.) Cl. Cl. Syn., 1,192; A. S. Atl., Tab. XLVIII, figs. 7—8 (no name). Eyrarbakki (S.), H. Js. Area : Eur., Am. Trachyneis velata (A. S.) Cl. Cl. Syn., 1, 194; A. S. Atl., Tab. XLVIII, figs. 33—34 (Nav. vel.). Reykjavik (S.W.), C. H. O., Stykkisholmur (S.W.), H.Js. Area: Afr., As., Am., Aust. Naviculse Lineolatae Cleve 1895. Cl. Syn., II, 10. Navicula ammophila Grun. var. flanatica Grun. Cl. Syn., 11,30; V. H. Syn., Suppl. A, fig. 17. HafnafjorSur (S.W.), H.Js. Area: Eur. Navicula anglica Ralfs var. snbsalsa Grun. Cl. Syn., 11,22; V. H. Trt., Tab. Ill, fig. 137 (N. a. v. subsalina). Skagafjor5ur (N.), Grid. Area: Eur. Navicula arenaria Donk. var. arcuata Per. Per. D. mar. 101, Tab. XIII, figs. 4 & 6. 4 samples (S.W. 3, N.W. 1). Area: Eur. MARINE DIATOMS FROM THE COASTS OF ICELAND 357 Navicula avenacea Breb. Cl. Syn., II, 15; V. H. Trt., Tab. V, fig. 241. (Schizonema Smithii Ag.) 7 samples (S.W. 3, N.W. 1, N. 2, E. 1). Area : Eur., Afr., As., Aust., Grl., A. S. Navicula Bolleana Grun. Cl. Syn., 11.25; A. S. Atl., Tab. XLVII, fig. 18. Grjotncs (N.). C. H. O. Area: Eur., Grl., A. S. Navicula bottnica Grim. Cl. Syn., 11,20; V. H. Syn., Tab. VII, fig. 33. 14 samples (S.W. 6, N.W. 2, N. 2, E. 4). Area: Eur., .Afr., As., Am., Grl., A. S. Navicula cancellata Donk. Cl. Syn., II, 30; V. H. Trt., Tab. Ill, fig. 128. AQalvik (N.W.), Lb. Area: Ubiquist, Grl., A. S. Navicula cancellata Donk. var. snbapiculata Grun. Cl. Syn., 1. c. ; A. S. N. S. D., Tab. II, fig. 22 (Nav. Gregorii). In the same sample as the main species. Area: Eur., Grl., A. S. Navicula digito-radiata Greg. Cl. Syn., 11,20; V. H. Trt., Tab. Ill, fig. 130. 4 samples (all S.W.). Area : Ubiquist, Grl., A. S. Navicula digito-radiata Greg. var. Cyprinus (Ehr.) W. Sm. Cl. Syn., I.e. V. H. Trt. 1. c,, fig. 131. Brokey (S.W.), H. Js., Latravik (N.W.), C. H. O. Area: Eur., Am., Grl. Navicula directa W. Sm. var. genuina Cl. Cl. Syn., 11,27; V. H. Trt., Tab. XXV, fig. 722. 24 samples (S. 5, S.W. 11, N.W. 3, N. 4, E.I). Area: Eur., Afr., As., Am., Grl., A. S. Navicula directa W. Sm. var. remota Grun. Cl. Syn. , I.e., A. S. N. S. D., Tab. Ill, fig. 2 (Nav. (Pinnularia) longa). Grjotnes (N.), C. H. O. Area: Eur., Afr., Am., Grl., A. S. Navicula directa W. Sm. var. subtilis Greg. Cl. Syn., I.e.; V. H. Trt., Tab. XXV, fig. 723. 17 samples ^S. 3, S.W. 11, N.W.I, N.I, E.I). Area: Eur., Grl., A. S. 358 ERNST 0STRUP Navicula distans W. Sm. Cl. Syn ., II, 35; V. H. Trt., Tab. Ill, fig. 133. 11 samples (S.\V. 10, N. 1). Area: Eur., Am., Grl., A. S. Navicula fortis Greg. CL Syn., II, 31; Donk. Br. D., Tab. VIII, fig. 8. Bildudalur (N.\V.), H. Js. Area: Eur., Am., Grl., A. S. Navicula inflexa Greg. CL Syn., 31 ; Per. D. mar., Tab. XIII, fig. 3. Olafsvik (S.W.), H. Js. Area : Eur., A. S. Navicula lanceolata (Ag.) Ktz. var. phyllepta Ktz. CL S}7n., II, 22 ; V. H. Trt., Tab. Ill, fig. 141. Stykkisholmtir (S.W.), H. Js. Area: Eur. Navicula peregrina Ehr. Cl. Syn., II, 18; V. H.Trt., Tab. Ill, fig. 101. 8 samples (S.I, S.W. 6, N.W.I). Area: Eur., Afr., As., Am., Grl., A. S. Navicula (Schizonema) Bryopsis (Ktz.) Grun. Grim. Bot. Cent. 1509; V. H. Syn., Tab. XV, fig. 26. 6 samples (S.W. 4, N. 2). Area: Eur. Navicula (Schizonema) mollis W. Sm. f. major Cl. Syn., II, 26; V. H.Syn., Tab. XV, fig. 22. Fossavik (E.), H. Js. Area: Eur., Afr., Am., Grl. Navicula (Schizonema) ramosissima Ag. Cl. Syn., 1,26; V. H. Trt., Tab. V, fig. 244. 35 samples (S. 2, S.\V. 18, N.W. 6, N. 6, E. 3). Area: Eur., Am., Grl. Navicula (Schizonema) ramosissima forma amplior CL Syn., I.e.; V. H. Syn., Tab. XV, fig. 3 (Schiz. amplius). Reykjavik (S.W.), H. Js. Area: Eur., Afr., Am. Naviculse Punctatse Cleve 1895. Cl. Syn. II, 37. Navicula granulata Bail. Cl. Syn., II, 48; Per. D. mar., Tab. XXVII, figs. 12—13 (N. Baileyana). Stykkisholmur (S.W.), H. Js. Area: Eur., As., Am., Aust, Grl. MARINE DIATOMS FROM THK COASTS OF ICELAND 359 Navicula humerosa Breb. Cl. Syn., II, 43; V. H. Trt.,- Tab. IV, flg. 182. 6 samples (S. 1, S.\V. 2, N.W. 1. N. 2). Area: Eur., Afr., As., Am., A. S. Navicula humerosa Breb. var. constricta Cl. Cl. Syn., 1. c. ; Per. D. mar., Tab. XXVII, fig. 21. Hafnarfj6r5ur (S.W.;, H. Js. Area: Eur., As. Navicula latissima Grun. Cl. Syn., 11,43; V. H. Trt., Tab. XXVII, fig. 762. Vestmannaeyjar (S.), H. Js. Area: Eur., As., A. S. Navicula pusilla Greg. Cl. Syn., II, 41 ; V. H. Trt., Tab. IV, fig. 186. 6 samples (S. 1, S.W. 5). Area : Ubiquist, A. S. Naviculae Lyratse Cleve 1895. Cl. Syn., II, 52. i Navicula abrupta Greg. Cl. Syn., II, 61 ; V. H. Trt., Tab. IV, fig. 162. Dyrafjordur (N.W.;, C. H. O., A5alvik (N.W., two samples), Lb. Area: Eur., Afr., As., A. S. Navicula abrupta Greg. var. densestriata var. nov. Tab. nost., fig. 9. Long: 32/<, lat: 11 /i, str. 16 in 10 /i. Valva linear!, apicibus cuneatis. Areis lateralibus angustis, mo- dice procul ab apicibus terminantibus. AQalvik X.W.), Lb. In spite of its small size and close striation this peculiar species shall probably be placed under the form-series of Nav. abrupta, as its short lateral areas especially seem to indicate its place there. Navicula forcipata Grev. Cl. Syn.. 11,65; Per. D. mar., Tab. XXI, fig. 28. 4 samples (S.I, S.W. 2, N.W.I). Area: Eur., Afr., Am., Grl. Navicula forcipata Grev. var. densestriata A. S. Cl. Syn., 11,66; Per. D. mar. 1. c., figs. 29—30. IsafjorSur S. 3, S.W. 17, N.W. 4, N. 4 . Area : Eur. Grammatophora oceanica forma minuscula Per. Per. 1. c. , 355, Tab. 1. c., fig. 13. 66 samples (S. 19, S.W. 38, N.W. 4, N. 5). Area : Eur. In a sample from Skerjafjordur (S.W.\ H. Js. I have found a curved Gram. oc. macil., of which I have given a figure in tab. nost. fig. 15. It has the dimensions: long. 73 //, lat. 6.5 //. Grammatophora serpentina Ehr. Per. D. mar., 356, Tab.LXXXVIII, figs. 2 — 5. Vestmannaeyjar (S.. 2 samples', H. Js. Area: Ubiquist. Rhabdonema Ktz. 1844. V. H. Trt., 360. Rhabdonema adriaticum Ktz. V. H. Trt., 360. Tab. XII, fig. 486a. Vestmannaeyjar (S., 3 samples), H. Js. Area: Ubiquist. Rhabdonema arcuatum (Ag.) Ktz. V. H. Trt., 360, Tab. XII, fig. 487 a. 303 samples (S. 38, S.W. 126, N.W. 21, N. 77, E. 36, S. L. 5). Area: Ubiquist, Grl., A. S. Rhabdonema arcuatum is a form which, as regards its outline, is variable, and in the samples examined by me, it appears with recti-linear as well as with more or less curved sides (see Cleve's var. ventricosum in Cl. Arct. S., 24, tab. IV, fig. 21). The curved species may perhaps be identical with Rhabd. Crozieri Grun. Concerning this see Mann, Albat. 322 under Tessela catena Ehr. 374 ERNST 0STRUP Rhabdonema minutum Ktz. V. H. Trt., 361, Tab. XII, fig. 488 a. 231 samples (S. 34, S.W. 113, N.W. 27, X. 42, E. 15). Area : Ubiquist, Grl., A. S. Rhabdonema robustum Grim. Grun. 0st. Diat., 422; A. S. Atl., Tab. CCXXI, figs. 17—23. Vestmannaeyjar (S.), H. Js. Area : Am. Striatella Agardh 1832. V. H. Trt., 362. Striatella delicatula (Ktz.) Grun. V. H. Trt., 363, Tab. XII, fig. 483 a. Skogarnes (S.W;), H. Js. Area: Eur., Afr., As., Am. CENTRIC^E Rhizosolenia (Ehr. Brightw.) Per. em. 1892. Gr. N. P., 46. Rhizosolenia hebetata Bail. f. semispina Hensen. .Gr. N. P., 55, fig. 67 b. Einarslon (N.), H. Js. Area: »Ozeanische Form, besonders im nordwestlichen Teile des Gebietes einheimisch«. (Gr. 1. c.). Chaetoceras Ehr. 1844. Gr. N. P., 58. Chaetoceras boreale Bail. Gr. N. P., 73, fig. 87. Arnarnes (N.) H. Js. Area : Ubiquist, Grl., A. S. Chaetoceras Diadema Ehr. Gr. N. P., 84, fig. 102 b. 5 samples (SAY. 2, N.W.I, N. 2). Area: Eur., As., Am., Grl., A. S. Only spores have been found. Chaetoceras furcellatum Bail. Gr. N. P., 95, fig. 121. Reykjavik (S.W.), H. Js. Area: Eur., Grl., A. S. Only spores have been found. Chaetoceras Ingolfianum Ostenf. Gr. N. P., 90, fig. 115. Hafranes (E.), H. Js. Area: Eur. Only spores have been found. MARINE DIATOMS FROM THE COASTS OF ICELAND 375 Thalassiosira Cl. 1872. Gr. N. P., 16. Thalassiosira gravida Cl. Gr. N. P., 18, fig. 12; spore, A. S. Atl., Tab. LVIII, fig. 44 (Coscinodiscus subglobosus). 7 samples (all S.W. . H. Js., Grid., C. H. O. Area: Eur., Am., Grl., A. S. Only spores have been found. Melosira Agardh 1824. V. H. Trt. 438. Melosira nummuloides (Bory) Ag. V. H.Trt. 440, Tab. XVIII, fig. 608. 26 samples (S. 3, S.W. 9, X. W. 4, N. 7, E. 3). Area : Ubiquist, Grl., A. S. Melosira sulcata (Ehr.) Ktz. V. H. Trt., 444, Tab. XIX, fig. 624. 81 samples S. 5, S.W. 61, X.W. 9, X. 6). Area : Eur., Afr., As., Am., Grl., A. S. Melosira sulcata 1'. radiata. Grun. Fz. J. L., 42, Tab. V, fig. 35. 8 samples (S.W. 6, X.W. 1, X. 1 . Area: Eur., A. S. Podosira Ehr. 1840. V. H. Trt., 447. Podosira hormoides (Mont.) Cl. & Gr. A. D., 118; A. S. N. S. D., Tab. Ill, fig. 40. 156 samples (S. 24, S.W. 79. X.W. 19, X. 17, E. 14, S. L. 3). Area: Eur., Am., Grl. In several of the samples examined by me Podos. horm. occurs with a diameter of up to 70 u and of a verv fine structure. For this / • *• reason it ma\r perhaps be considered as a forma major of Podos. horm. var. glacialis Grun., see Fz. J. L., 56, tab. V, fig. 32. I have found it with the more distinct punctuations indicated in the figure, as well as without these. Hyalodiscus Ehr. 1854. V. H. Trt.., 448. Hyalodiscus subtilis Bail. Per. D. mar., 443, Tab. CXIX, fig. 7. 7 samples (S.W.I, X. 3, E. 3). Area: Eur., Afr., As., Am., Grl., A. S. Hyalodiscus subtilis Bail. var. scoticus (Ktz.) Grun. Per. 1. c. 443, Tab. 1. c., fig. 8. 209 samples (S. 28, S.W. 110, X.W. 24, X. 39, E. 7, S.L.I). Area: Eur., Am., Aust., Grl., A. S. Isthmia Ag. 1830. Per. D. mar., 375. Isthmia nervosa Ktz. Per. D. mar., 375, Tab. XCI. 64 samples (S. 20, S.W. 24, X.W. 3, X. 7, E. 7, S. L. 3). Area: Eur., Am., Grl., A. S. 376 ERNST 0STRUP Biddulphia Gray 1831. V. H. Trt. 466. Biddulphia antediluviana (Ehr.) H. V. H. V. H. Trt., 475, Tab. XXI, fig. 642. Yestmannaeyjar S.), H. Js. Area: Eur., Afr.. Am. Biddulphia aurita (Lyngb.) Breb. V. H. Trt., 471, Tab. XX, fig. 631. 180 samples (S. 14, SAY. 83, N.W. 29, N. 34, E. 17, S. L. 3). Area : Eur., Afr., As., Am., Grl., A. S. Biddulphia (Odontella) obtusa Ktz. Per. D. mar., 381 ; V. H. Syn., Tab. C, figs. 11—14. 4 samples (SAY. 2, N.W. 1, E. 1). Area: Ubiquist. Trigonium Cl. 1867. Per. D. mar., 377. Trigonium arcticum (Bright.) Cl. Per. D. mar., 379. Brightv. Trie., Tab. IV, fig. 11 (Triceratium arct.). Flatey by Husavik (N.), H0rr. Area: Eur., Afr., Am., Grl., A. S. Actinoptychus Ehr. 1838. V. H. Trt., 493. Actinoptychus undulatus (Ehr.) Ralfs. V. H. Trt., 496, Tab. XXII, fig. 648. 5 samples (all SAY.), Grid., H. Js. Area: Ubiquist, Grl. Actinocyclus Ehr. 1840. V. H. Trt., 522. Actinocyclus Barkleyi (Ehr.) Grun. Ratt. Actinoc., 158; V. H. Syn., Tab. CXXIV, fig. 12. Yestmannaeyjar (S.), H. Js. Area: Am., Aust. Actinocyclus crassus H. V. H. V. H. Trt., 523, Tab. XXIII, fig. 660. Yestmannaeyjar (S.), H. Js., Reykjavik (S.W.), H. Js. Area: Ubiquist. Actinocyclus Ralfsi (W. Sm.) Ralfs. Per. D. mar., 414, Tab. CXIII, fig. 2. Yestmannaeyjar (S.), H. Js., Hafnafjor5ur (SAY.;, H. Js., Reykjavik (S.W.), H. Js. Area: Ubiquist, ..Grl. MARINE DIATOMS FROM THE COASTS OF ICELAND 377 Actinocyclus subtilis (Greg.) Ralfs. V. H. Trt., 524, Tab. XXIII, fig. 661. Melvik (S.W.), C. H. O. Area: Ubiquist. Coscinodiscus Ehr. 1838. V. H. Trt., 525. Coscinodiscus excentricus Ehr. V. H. Trt., 531, Tab. XXIII, fig. 666 Steingrimsfjordur (N.), H. Js. Area : Ubiquist, Grl., A. S. The Botany of Iceland II. 25 TABULAR SURVEY ERNST 0STRUP, MARINE DIATOMS FROM THE COASTS OF ICELAND 381 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Achnanthes brevipes Universal distribution Distribution in the different parts of the coasts of Iceland Eur. Afr. As. Am. Aust. Grl. A.S. S. s.w. N.W. N. E. X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X linearis intermedia .... parvula var groenlandica . Hauckiana longipes Actinocyclus Barkleyi crassus Ralfsi subtilis Actinoptychus undulatus Amphipleura rutilans Amphora angusta crassa cymbelloides exigua laevis lineolata marina Proteus contigua Pusio robusta Terroris Biddulphia antediluviana aurita obtusa Caloneis brevis 26 16 21 23 16 18 13 15 21 15 11 7 382 ERNST 0STRUP Jl V2 J3 54 J5 !6 M J8 19 10 1 r2 3 4 5 6 •7 8 9 0 1 2 3 4 5 6 .7 •8 9 (Caloneis brevis) distoma .... Universal distribution Distribution in the different parts of the coasts of Iceland Eur. Afr. As. Am. Aust. Grl. A. S. S. S.W. N.W. N. E. X X X X X X X X X X X X X X X X X X X X X X X X X X X X X 1 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X ^ X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X formosa Liber genuina elongata linear is Campylodiscus angularis biangulatus fluminensis Samoensis Thureti Chaetoceras boreale Diadema furcellatum Ingolfianum Cocconeis brittannica costata dirupta . decipiens Siqma . — grata . molesta Pelta pseudomarginata Scutellum . . ornata parva stauroneiformis . Coscinodlscus excentricus Dimeregramma minus nanum 27 12 16 18 11 17 1 17 12 18 13 12 8 MARINE DIATOMS FROM THE COASTS OF ICELAND 383 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 Diploneis sestiva Universal distribution Distribution in the different parts of the coasts of Iceland Eur. Afr. As. Am. Aust. Grl. A. S. S. S.W. N.W. N. E. X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X bomboides media chersonnensis coffseiformis constricta contigua Eudoxia Crabro minuta didyma elliptica grandis fusca subrectangularis . incurvata interrupta lineata .... littoralis major Smith! splendida subcincta Fragilaria hyalina striatula vitrea . . Gomphonema exiguum kamtschaticum Grammatophora angulosa hamulifera .... islandica arcuata marina oceanica macil minuta serpentina Hantzschia marina — virgata 31 17 19 22 13 17 16 18 24 19 19 13 93 94 95 96 97 98 99 LOO L01 102 103 104 L05 106 L07 108 109 L10 111 L12 113 L14 L15 116 117 L18 119 120 121 122 123 L24 Hyalodiscus subtilis Universal distribution Distribution in the different parts of the coasts of Iceland Eur. Afr. As. Am. Aust. GH.'A.S. S. S.W. N.W. N. E. X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X scoticus Isthmia nervosa - . Licmophora anglica Jurgensi Oedipus — elongala paradoxa .... Mastogloia elliptica Dansei exigua Melosira — nummuloides sulcata radiata Navicula abrupta . Acus aramophila flanatica . . . anglica subsalina arenaria arcuata avenacea Bolleana bottnica cancellata subapiculata . . digito-radiata Cyprinus directa — remold subtilis distans . • • elegans forcipata • 32 15 13 18 7 19 19 9 23 20 17 12 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 (Navicula forcipata) densestriata fortis Universal distribution Distribution in the different parts of the coasts of Iceland Eur. Afr. As. Am. Aust. Grl. A. S. S. s.w. N.W. N. E. X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X 1 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X fusiformis ostrearia .... granulata Grevillei halophila Hennedyi circumsecta . . . humerosa constricta .... inflexa lanceolata phyllepta . . . latissima Libellus Lyra Ehrenbergi — atlantica mutica Cohni palpebralis angulosa peregrina pusilla rhombica ulvacea (Schizonema) Bryopsis . mollis ramosissima . . f. amplior ... . Nitzschia acuminata angularis af finis apiculata bilobata dissipata Acula lanceolata marginulata paradoxa Sigma . rigidct socialis 39 15 1 24 23 9 19 18 13 28 16 14 8 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 (Nitzschia) Tryblionella littoralis vitrea salinarum Universal distribution Distribution in the different parts of the coasts of Iceland Eur. Afr. As. Am. Aust. Grl. A. S. S. S.W. N.W. N. E. X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X - X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X 11 X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X Pinnularia qvadratarea Trevelyana Plagiogramma Gregorianum Pleurosigtna cuspidatum elongatum ."...' longum Nubecula intermedia... Stuxbergi Podosira hormoides Rhabdonema adriaticum arcuatum minutum robustum Raphoneis amphiceros Rhoicosphenia curvata Rhopalodia Musculus . . Stauroneis constricta . . Gregory! • salina Striatella delicatula 19 12 11 18 12 9 6 16 8 8 7 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 Surlrella fastuosa Universal distribution Distribution in the different parts of the coasts of Iceland Eur. Afr. As. Am. Aust. Grl. A. S. S. S.W. N.W. N. E. X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X • X X X X X X X X X X X X X X X X X ^ X X X X X X X X X X X X X X X X X X X X X X X X X X X Synedra affinis — gracilis fasciculata — lancettula — parva ... . rupicola — tabulata crystallina Gailloni Hennedyana investiens kamtschatica provincialis pulchella Thalassionema nitzschioides Thalassiothrix Frauenfeldi Thalassiosira gravida Trachyneis aspera intermedia pulchella . . . Clepsydra velata .... Trigonium arcticum Tropidoneis lepidoptera Total . . . % 195 95 113 184 75 115 107 87 145 101 92 64 93 45 54 64 36 55 49 42 69 48 44 31 388 ERNST 0STRUP As regards the universal distribution, it appears from the above list, that the Icelandic coastal flora, as far as the Diatoms are con- cerned, has a predominant Europeen character, but about one half of the European species can also occur in colder seas. The list of the distribution of the Diatoms in the different parts of the coast shows, that out of 209 species found in the samples, 145 or 69% were found in S.W., 101 or 48% in N.W., 92 or 44% in N., 87 or 42 % in S. and 64 or 31 % in E. The Diatom-life therefore is most abundant on the South- West coast. List of the species found in more than 50 samples. Rhabd. arcuat Total 438 samples S. 58 samples S.W. 191 samples N.W. 30 samples N. 98 samples E. 53 samples Number of samples °/o Number of samples % Number of samples °/o Number of samples % Number of samples % Number of samples °/o 303 231 209 180 174 160 156 155 143 125 119 82 91 81 66 64 62 60 51 69 53 48 41 40 37 36 35 33 29 27 19 21 18 15 15 14 14 12 38 34 28 14 13 18 24 '31 17 23 10 12 15 5 19 20 17 16 10 66 60 48 24 22 31 41 53 29 40 17 21 26 9 33 34 30 28 17 126 113 110 83 77 74 79 98 74 61 49 30 40 61 38 24 25 34 33 66 59 58 43 40 39 41 51 39 32 26 16 21 32 20 13 13 18 17 21 27 24 29 27 15 19 11 16 10 18 5 10 9 4 3 5 4 3 70 90 80 97 90 50 63 37 53 33 60 17 33 30 13 10 17 13 10 77 S 34 50 38 17 12 27 21 28 13 16 6 5 7 8 4 4 79 43 40 35 51 39 17 12 28 21 29 13 16 6 5 7 8 4 4 36 15 7 17 17 15 14 3 7 10 14 20 10 0 0 7 7 2 1 68 28 13 32 32 28 26 6 13 19 26 38 19 0 0 13 13 4 2 rninut. . . . Hval. subt. v. scotic. . tj Biddiilph. aurit Svn. aff. -}- var Coccon. Scutell Podos. horm Grammat. mar Rhoicosph. curv Grammat. ang. v. isl Goccon. cost Fragil. striat Gomphon. exig Melos. sulc Grammat. ocean, v. min.. Isthm. nerv Syn. invest. Grammat. ang. Trach. asp. var. pnlch. . . . Not considering N. W. in the above list, which, owing to the small number of samples, gives a misleading percentage, it appears, that, of the frequently occurring species, the following are especially prominent: in S. (with more than 50%): Rhabd. arc. (66 %), Rhabd. minut. (60 %), Gramtph. marina (53 %). MARINE DIATOMS FROM THE COASTS OF ICELAND 389 In S.W. (with more than 50°/u): Rhabd. arc. (66%), Rhabd. min. (59%), Hyal. subt. scot. (58%), Gramtph. marina (51%). In N. (with more than 40%): Rhabd. arc. (79%), Syn. nil. -f var. (51 %), Rhabd. min. (43 %). In E. (with more than 30%): Rhabd. arc. (68%), Frag, strial. (38 %), Bidd. aur. (32 %), Syn. aff. + var. (32 %). This shows, that Rhabd. arc. ist the most predominant Diatom along the coasts of Iceland. CHARACTERISING FORMS. By » characterising forms « I understand species, which, by their, frequent occurrence in a sample, may be considered to be charac- teristic for this. » Characterising forms « are of course far from being always found in a sample, but on the other hand, several such forms may very well be present in the same sample. In the list below, I have given a synopsis showing the genera or species of Diatoms characteristically associated with the various genera of Algae. Where a figure is attached to the name of the Diatom it indicates the number of the samples in which the genus Rhodophyceae Number of samples 125 1 Antithamnion 7 Grammatophora (2), Hyalodicus scoticus, Podosira. 2 Bangia 6 Rhabd. arc. 3 Calithamnion 6 Achnanthes, Cocconeis, Grammatophora, Rhoicosphenia curv., Rhabd. arc. (2), Synedra. 4 Ceramium 9 Amphipleura rutilans, Podosira. 5 Chantransia 10 Cocconeis, Frag, striat., Licmophora (2), Rhabd. arc.. Rhabd. min. (2), Synedra (2). 6 Delesseria 7 Cocconeis, Isthmia (2). 7 Halosaccion 9 Rhabd. arc., Rhabd. min. (2). 8 Lomentaria 2 Isthmia. 9 Melobesia 3 Grammatophora. 10 Petrocelis 5 Isthmia. 11 Phyllophora 1 Cocconeis. 12 Potysiphonia Cocconeis (2), Grammatophora (3), Isthmia, Rhabd. 15 arc. (2). 13 Porphyra 10 Licmophora (2), Synedra. 14 Ptilota 4 Cocconeis. Grammatophora. 15 Rhodochorton 19 Cocconeis (2), Gomphonema cxigmiin, Grammatophora (3), Rhabd. arc. (3), Rhoicosphenia curv., Synedra (2X 16 Rhodomela 7 Cocconeis (2), Isthmia, Licmophora, Rhabd. arc. (2). 17 Rhodymenia 4 Licmophora. 18 Turnerella 1 Rhabd. min. 390 ERNST 0STRUP or species in question is found ; where no figure is added it means, that the genus or species in question has only been found in one sample. The following are some of the more conspicuous characterising forms on Rodophyceae: Rhabd. arcuat in 12 samples = 9.6 %, Cocconeis and Gramma- tophora each in 11 samples : : 8.9%, Licmophora and Synedra each in 6 samples = 4.8 %>. Phaeophyceae Number of samples 108 1 Ascocyclus 1 Frag, vitrea. 2 Ectocarpus 38 Biddulphia aur., Gomphonema exigtmm, Frag, striat. (3), Hyalodiscus scoticus, Licmophora, Navicula rhom- bica, Podosira, Rhabd. arc. (2), Rhoicosph. cur.. Synedra (5). 3 Elachista 8 Rhabd. arc. (2). 4 Fucus 6 Isthmia, Rhabd. arc. 5 Isthmoplea 6 Frag, striat., Synedra. 6 Laminaria 1 Grammatophora, Podosira, Navic. (Schizonema). 7 Leptonema 2 Rhoicosph. curv., Synedra. 8 Lithoderma 4 Frag, striat., Grammatophora, Licmophora (3). 9 Myrionema 6 Riddulphia aur.. Cocconeis (2), Frag, vitrea, Podosira. Rhabd. min. 10 Phyllitis 7 Cocconeis (2), Frag, striat. 11 Pogotrichum 9 Riddulphia aur., Cocconeis, Podosira, Rhabd. arc., Sy- nedra (2). 12 Punctaria 1 Frag, striat., Synedra. 13 Ralfsia 8 Diploneis incurvata. 14 Sphacelaria 7 Cocconeis (3\ Rhabd. min. 15 Stictyosiphon 4 Licmophora. The following are some of the more conspicuous and charac- terising forms on Phaeophyceae: Synedra 10 samples, or 9.3% of the samples, Cocconeis 8 samples or 7.4%, Fragilaria striat. 7 samples or 6.5%, Rhabd. arc. 6 samples or 5.6%. The following are some of the more conspicuous, characterising forms on the Chlorophyceae: Cocconeis 19 samples or 20.6% of the samples, Fragil. striat. and Synedra each 6 samples or 6.6 %, Lic- mophora and Rhabd. arc. each 5 samples or 5.4 %. It appears therefore, that on the Rhodophyceae , Rhabd. arc. and to some extent also Cocconeis and Grammatophora principally are the characterising forms; on the Phaeophyceae the Synedra MARINE DIATOMS FROM THE COASTS OF ICELAND 391 Chlorophyceae Number of samples 92 1 Acrosiphonia 25 Cocconeis (8), Licmophora (3), Frag, striat, Hliabd. arc. (4), Synedra. 2 Chaetomorpha 2 Cocconeis, Rhabd. arc. 3 Cladophora 15 Amphora, Cocconeis (6), Synedra. 4 Codiolum 2 Frag, striat. 5 Enteromorpha 20 Achnanthes, Cocconeis (2), Melosira num.. Nnvicula bottnica, Rhab. min. (2), Synedra (3). 6 Monostroma 11 Frag, striat., Melosira num. 7 Ochlochaete 1 Cocconeis, Synedra. 8 Rhizoclonium 5 Achnanthes (2), Cocconeis, Navicula pusilla. 9 Ulvella 1 Frag, striat. 10 Urospora 10 Biddulphia aur., Fragil. striat. (2), Licmophora (2), Rhabd. min. is the most conspicuous form, while Cocconeis takes the lead on the Chlorophyceae. When examining how matters stand as regards the occurrence of the characterising forms in the 6 groups of Marine Alga? given by Helgi Jonsson in Bot. of I eel. part 1, pages 58 — 62, it appears, that in Group A, The Arctic Group I have found 1 charact. form in 3 samples B, The Subarctic Group, Subdiv. I B, II C, The Boreal-Arctic Group D, The Cold-Boreal Group E, The Warm-Boreal Group 13 36 22 37 1 - 14 - 32 - 17 - 32 - 5 This shows, that the characterising forms are most frequent in groups B, C and D, which agrees well with the paramount European character of the Icelandic coastal Diatom-flora. Finally, considering the occurrence of the characterising forms during the different months of the year, as far as this has been given in the samples, the facts are the following: Number of samples Charact. forms °/o Number of samples Charact. forms % T o m i o t^xr 3 0 10 37 72 107 1 0 5 16 27 37 33 0 50 43 38 35 July. 57 51 42 18 0 0 12 14 19 2 0 0 21 27 45 11 0 0 T^AVlTMl 51 T* %/ August . March September . Anril October Mav. November December June 392 ERNST 0STRUP i Apart from the months, January, March and October, in which less than 37 samples are present, the rest must be placed in the following order, according to their percentages : September 45, April 43, May 38, June 35, August 27, July 21. This shows, that the number of the characterising forms in- creases with July in both directions. MARINE DIATOMS FROM THE COASTS OF ICELAND 393 LITERATURE BRIGHTWELL. TH. On the genus Triceratium ... Quart. Journ. Micr. Soc. I. London. 1853. (Bright. Trie.) CLEVE, P. T. On Diatoms from the Arctic. Sea. Bih. t. K. Sv. Vet. Akad. Handl. B. I. Nr. 13 Stockh., 1873. (Cl. A. S.) CLEVE, P. T. Diatoms collected during the Expedition of the Vega. Vega-Exped. Vetensk. Arbet. lakttag. B. II. Stockh., 1883. (Cl. Vega Exp.) CLEVE. P. T. Synopsis of the Naviculoid Diatoms I— II. K. Sv. Vet.-Akad. Handl. B, 26, Xr. 2 and B. 27, Nr. 3. Stockh., 1894-95. (Cl. Syn.) CLEVE, P. T. und A. GRUNOW. Beitriige zur Kenntniss des Arctischen Diatomeen. K.S. Vet.-Akad. Handl. B. 17. Xr. 2. Stockh., 1880. (Cl. & Gr. A.I). DE TONI, J. B. Sylloge Bacillariearum omnium hucusque cognitarum I — III Patavii MDCCCXCI— MDCCCXCIV. (De Ton. Syll.) DONKIN, A. S. The Xatural History of the British Diatomaceae. London. 1871 — 73. (Donk. Br. D.) GRAN, H. H. Nordisches Plankton. Kiel und Leipzig, 1905. (Gr. N. PI.) GREGORY, W. On the Post-tertiar\^ lacustrine Sand . . . from Glenshira. Trans, micr. Soc. Ill— IV. London, 1856. (Greg. T. M. S.) GREGORY, W. On new forms of Marine Diatoms, found in the Firth of Clyde and in Loch Fyne. Trans. Roy. Soc. Edinb. Vol. XXI. Edinburgh. 1857. (Greg. Clyd.i GRUNOW. A. Die osterreichischen Diatomaceen. Verh.Zool. Bot. Ges. B. 12. Wien, 18(52. (Grun. 0st. Diat.) GRUNOW, A. Vorlaufige Bemerkungen zu einer systematischen Anordnung cler Schizo- nema-und Berkeleya-Arten . . . Bot. Centralblatt B. IV. Xr. 47 & 48. Grun. Bot. Centrb.) GRUNOW, A. Die Diatomeen von Franz Josefs- Land. Denk. Akad. Wiss. Wien. B. XLVIII, Wien. 1884. (Gr. Fz. J.) HEIBEUG, P. A. C. Conspectus criticus Diatomacearum Danicarum. Kjobenhnvn. 1863. (Heib. D. D.) KUTZING, F. T. Die kieselschaligen Bacillarien oder Diatomeen. Xordhausen. 18(55. (Ktz. Bac.) MANN, A. Report on the Diatoms of the Albatross Voyages in the Pacific Ocean. 1888—1904. Smithson. Instit. Contr. fr. the Unit. Stat. Nation. Herbnr. Vol. X. Part 5. Washington, 1907. (Mann Albat.) PANTOCSEK, J. Beitrage zur Kenntniss der fossilen Bacillarien Ungarns. I— III. Nagy Tapolosany, 1886-93. (Pant. Ung ' PERAGALLO, H. Monographic du genre Pleurosigma. Le Diatomiste I. Paris. 1890- (Per. Pleur.) PERAGALLO, H. & M. Diatomees marines de France et des districts voisins. Grez-sur- Loing, 1897—1908. (Per. D. mar. The Botany of Iceland. Vol. I, part II. 26 394 ERNST 0STRUP. MARINE DIATOMS FROM THE COASTS OF ICELAND RATTRAY. J. A revision of the genus Actinocyclus Ehr. Journ. Quek. Micr. Club II, 4. London, 1890. (Ratt. Actinoc.) SCHMIDT, ADOLPH. Die in den Grundproben der Nordseefabrt . . . cnthaltenen Diato- maceen. II. Jahresber. d. Komm. z. Unters. d. deut. Meere in Kiel, Rerlin, 1874. (A. S. N. S. D.) SCHMIDT, ADOLPH. Atlas der Diatomaceenkunde, Aschersleben 1874 not yet com- pleted. (A. S. Atl.) SMITH. WILLIAM. A Synopsis of the British Diatomacese I — II, London, 1853 — 1856. (W. Sm. Syn.) VAN HEURCK, HENRI. Synopsis des Diatomees de Belgique I — IV, Anvers, 1880—85. (V. H. Syn.) VAN HEURCK, HENRI. Traite des Diatomees. Anvers. 1899. (V. H. Trt.) 0STRUP, E. Marine Diatomeer fra 0stgronland. Medd. om Grenl. XVIII, Kjobenh.. 1896. (0st. 0stg. mar.) OSTRUP, E. Kyst-Diatomeer fra Grenland. Medd. om Grl. XV. Kjebenh., 1898. (0st. Kyst. D ) EXPLANATION OF PLATE Page 1. Caloneis brevis (Greg.) Cl. var. vexans Grun 350 2. Diploneis contigua (A. S.) Cl. var. Eudoxia A. S 351 3. Diploneis notata sp. nov 352 4. Diploneis? inseqvalis sp. nov 353 5. Navicula glabra sp. nov 353 6. Navicula Kryokonites Cl. var. ? islandica var. nov 354 7. Navicula (Libellus) complanata Grun. var.? 355 8. Gomphonema kamtschaticum Grun. var. islandicum var. nov. ." 356 9. Navicula abrupta Greg. var. densestriata var. nov 359 10. Navicula Lyra Ehr. var. islandica var. nov 360 1 1 . Cocconeis levis sp. nov 363 12. Achnanthes islandica sp. nov 365 13. Nitzschia islandica sp. nov 368 14. Synedra curvata sp. nov 370 15. Grammatophora oceanica Ehr. var. macilenta W. Sm. forma arcuata . 373 Botany of Iceland. Vol. I. Plate 1. 8 11 12 9 3 I a I, 14 15 Pacht k. Crone phototyp. 4. THE BRYOPHYTA OF ICELAND BY AUG. HESSELBO WITH 39 FIGURES IN THE TEXT INTRODUCTION. PREVIOUS to the time when Gronlund made botanical collections in Iceland (1868 and 1876) the Bryophyta of the island was very little known. Earlier botanists, who occasionally collected speci- mens also of the Bryophyte Vegetation, have only exceptionally given information as regards localities, and the older lists consist merely of an enumeration of species without any information as regards dis- tribution or frequency. To this must be added that the older deter- minations of species are very uncertain, and in many cases un- doubtedly erroneous or quite improbable, and that the lists are compiled quite uncritically without stating the name of the collector or the source of the information. For instance, more than half of the 149 mosses and 54 hepatics enumerated in Lindsay's list are undoubtedly wrongly determined, and the majority of them beyond doubt do not occur in Iceland. Therefore, in preparing the following list of the Bryophyta- of Iceland, older records have been taken into consideration only when it has been possible to verify them by means of specimens in the collections. The material dating from older collections (previous to Gron- lund's) is but very scanty. Morch was the first to contribute anything of importance to our knowledge of the Bryophyta of Iceland. In 1820 he collected a rather considerable number of species, among which are many that were not found again until quite recently, and even several which have not since been found by others. Morch's collections are in the Botanical Museum in Copenhagen, but unfortunately he has in only quite a fewr cases recorded the habitat on the wrappers. W. J. Hooker (1809), Lindsay (1860) and Car oil (1861) collected mosses and hepatics in Iceland, but as mentioned above, Lindsay's list,- in which 398 A. HESSELBO these finds are enumerated, is so full of mistakes that it is quite worthless. Japetus Steenstrup collected (1839-40) some Bryophyle samples in West and North Iceland and in the interior of the country. But it was not until Gronlund's investigations that the foun- dation was laid of a real knowledge of the Bryophyte Vegetation of Iceland, he not only critically revised the older lists, but also */ «/ prepared lists of his own collections. It was also Gronlund who was the first to give real descriptions of moss societies. Gronlund's journeys in 1868 and 1876 extended over West and North Iceland, from Reykjavik across Esja to Borgarfjordur and thence to Skagafjordur, Eyjafjordur and Myvatn. He did not visit East, South and North-wrest Iceland. In recent times the Iceland botanists Ola fur Davidsson, Stefan Ste fans son and Helgi Jonsson have contributed con- siderably to our knowledge of the Bryophyta of Iceland. Olafur Davidsson (died 1902) made, during 1899— 1900, very considerable and valuable collections in North Iceland around Eyjafjordur and Skagafjordur and on the small island of Grimsey north of the Arctic Circle. His collections, which belong to the Reykjavik Museum, have only now been determined. Stefan Ste fans son, the head of a school in Modruvellir and member of the Althing up to 1916, has made collections during many years, especially in North and North-east Iceland. The greater part of his material is published in Gronlund's list. Helgi Jonsson, Dr. phil. and teacher in Reykjavik, on his numerous journeys to almost all the different parts of the island, has everywhere collected specimens of the Bryophyte Vegetation, and in his descriptions of the vegetation of Iceland has usually men- tioned the Bryophyta also. His collections, which are preserved in the Botanical Museum in Copenhagen, are determined by C.Jen- sen. Besides the botanists mentioned above, a few others have also occasionally collected specimens of the Bryophyte Vegetation. C. Ostenfeld, during a few short visits, has especially investigated the lava-fields and the hot springs near Reykjavik and on the peninsula of Reykjanes. A. Feddersen (1884 — 86) made some collections in South and West Iceland. Dr. C. Hansen, Professor Th. Thoroddson and Petur Sophoniasson collected mosses THE BRYOPHYTA OF ICELAND 399 in several places. The majority of these collections are determined by C.Jensen and included in Gronlund's list (1895). My own investigations were made on three journeys, viz. in 1909 and 1912 by the aid of the Carlsberg Fund, and in 1914 by the aid of the Botanical Travelling Fund, and Japetus Steen- strup's Legacy. In 1909 I investigated in the beginning of June the region around Reykjavik and Hafnarfjordur, and made a live day's trip to the Esja mountains. On June 9th I sailed to Horna- fjordur in South-east Iceland, and after staying a few days there went straight through East Iceland to Seydisfjordur, where I arrived on June 30th. On the way I stopped at several farms, viz. Stafa- fell, Hof, Djupivogur, Berufjordur, Hoskulstadr and Vallanes. On July 9lh I took the coast steamer to Husavik in North Iceland, and after some days sojourn there went into the interior of the is- land across As and Svinadal to Reykjahlid near Myvatn, and after having stayed a few7 days there to Akureyri. Unfortunately investigation in this interesting region was almost entirely prevented by continual rain and fog. I stayed five days in Akureyri and then continued my journey westwards through North Iceland to Stadur near Hrutafjordur, stopping at the farms Tvera in 0xnadalur, Vidiimri, Vidivellir, Geitaskard, Hnausar and Lsekjarmot. From Stadur I rode across Haukadalsheidi and Brattabrekki to the farm Dals- mvnni in Nordredalur, wrhere I arrived on August 2nd. After stav- v O «. ing a few days there in continual rain, I was obliged to abandon my original plan of travelling by land to Reykjavik and, instead, to ride to Borgarnes and take the steamer to Reykjavik. In 1912 I arrived at Reykjavik on June 2nd and rode thence past Kolvidarhol to Reykir, where the vegetation around the hot springs was investigated, and thence to Skalholt, Laugardalur and Thingvellir, staying a few days at each place, and then back again to Reykjavik, whence I sailed on June 15th to Dvrafjordur in North-west Iceland. On the way I had an opportunity during a 24 hours stay in Stykkisholmur to investigate the immediate neigh- bourhood. After a three days stay at Dvrafjordur I rode on June 20th to Isafjordur, whence, during the following three weeks, I made numerous excursions, partly, on foot, to the surrounding country and to Sugandafjordur, and partly to the north-west side of the fjord and the district around Jokulsfjordur, to Hesteyri and the whole tract of land from the head of Jokulsfjordur to Stadur, and from Baeir to Arngerdareyri. 402 A. HESSELBO I. LIST OF THE BRYOPHYTA. I. HEPATIC^E. FAM. RICCIACEiE. 1. Riccia bifurca Hoffni. N. Iceland: Hrossaberg (St.)!; Vidimxri (Grl.)!; Mj'vatn!. S. Iceland: Near Reykjanes lighthouse (Ostf.)!; Kverkfjall (Wegener.)!. In all these localities it grows on warm, damp clayey flats near hot springs. Near Myvatn where it grew abundantly around fuma- roles, from which issued aqueous vapours containing sulphuretted hy- drogen the temperature of the soil was about 40 01 about one cm. below the surface. Near Reykjanes lighthouse Ostenfeld (Bot. Tids- skrift, vol. XXII, 1899, p. 239: gives the temperature of the soil as 20° -30°. All the plants investigated bore capsules. 2. Riccia sorocarpa BischofT. N. Iceland: Reykjalaug in Fnjoskadal (O. D.)!. S. Iceland: Grafarbakki near the Minni Laxa (F.)!; Laugarashver!. Like the preceding species, R. sorocarpa grows on warm, damp clayey flats. Near Laugarashver it was found abundantly on clayey slopes stretching down towards the boiling hot spring. There the tem- perature of the soil was about 25° -30°. All the plants investigated bore capsules which in the plants from Laugarashver were fully ripe at the end of July. 3. Riccia crystallina L. S. Iceland: Thorlakshver near Skalholt!. (27. 7. 1914). The plants, which had fully developed capsules, grew widely scat- tered on clayey flats, otherwise bare of vegetation, around some small holes from whence issued boiling water accompanied by vapours slightly impregnated with sulphuretted hydrogen. Note. Riccia glauca L. is mentioned by Zoega and is recorded by Hornemann as occurring abundantly near Geysir. But as no speci- mens of it arc to be found in the collections, and during the search made in 1914. no species of Riccia were found near Geysir, it is im- possible to determine what species is meant. Here and throughout the book the centigrade scale is meant. THE BRYOPHYTA OF ICELAND 403 FAM. MARCHANTIACE^:. 4. Sauteria alpina Xees. X. Iceland: Graenuhnukr in Brattafjallgardi between Modruvellir and Bru (St.). 5. Reboulia hemisphaerica (L.) Raddi. SW. Iceland: Hafnarfjordur H. J.)!. S. Iceland: Drangshlid H. J. Holt!; near Skogafos!: Seljaland!. This plant was found only in tbe southern part of the country, but it appears to occur there rather frequently. Near Hafnarfjordur it was found in a lava cave; in S. Iceland it was collected everywhere from the somewhat damp faces of tuff rocks, especially from the base of the sides of illuminated caves in tuff cliffs; in this situation it usually grew in company with Preissia commutata, Feyatella, Marchantia, Anoec- tangium compaction. Distichium montanum, etc. It was found every- where in fruit which was almost ripe at the end of July. 6. Fimbriaria pilosa (Wahlb.) Taylor. N. Iceland: Hof O. D.) ! ; Boggverstadadalur (O. D. :. XW. Iceland: Baeir on Snaefellsstrand!. Near Baeir it grew abundantly on a stony slope facing south and stretching down towards the sea, upon rather dry, humus-covered rocks. It was everywhere collected in fruit which near Ba?ir had just ripened on June 6. 1912. 7. Fegatella conica Cord a. Hcpatica conica Lindb. S. Iceland: Drangshlid (H. J. !: Merkjafoss (F. !; Breidabolstadr!; Barkastadr!; Seljaland!; Holt!; Drangshlid!; Skogafos!. This plant was not found except in S. Iceland, but there it was common in all the parts which were investigated. It grew there every- where on faces of tuff rocks, especially on those of caves and clefts, and more particularly on the faces with a southern exposure where it may occur very abundantly, sometimes on the damp tuff rocks them- selves and sometimes creeping over mosses, for instance Hijpmim fili- cimim, Eurynchium Swcirl:ii, etc. Sterile specimens only have been found. 8. Preissia commutata (L.) Nees. Chomocarpon quadra tus Scop.) Lindb. N. Iceland: Hof. fr. (O. D. ':!; Modruvellir O.I). !; Hrossaberg on warm clayey flats, fr. (St.)!; Stora Gja near Myvatn !. XW. Iceland: Stadr on Snaefellsstrand, fr. (Stp. !. \V. Iceland: common near the hot springs in Reykholtdalur!; Hafnarfjordur!. S. Iceland: Thingvellir Grl.:! 404 A. HESSELliO Laugardal Grl.;!): Reykjanes near hot springs (Ostf.)!; common every- where on faces of tuff rocks in Fljotshlid and below Eyjafjallajokull!. Preissia commntata occurs both on more or less damp ground and on damp rocks, and also on warm clayey flats near hot springs. In the last situation, as in Rcykholtdalur , it covers large areas on slopes stretching down towards the boiling hot water. In E. Iceland it has not yet been found: in X. and N\V. Iceland it is rather rare and grows there on damp rocks, along river-banks or in rock-clefts. In S. and S\V. Iceland it is frequent in lava-clefts near Thingvellir and Hafnarfjordur, and in S. Iceland proper it is very common. There it grows at the base of, or some wa\r up the rock faces, especially upon those with a southern exposure, or in sheltered clelts, and often occurs in great abundance, and fruiting richly. The fruit was not quite ripe even at the end of July. 9. Marchantia polymorpha L. Common all over Iceland on damp soil, on rocks, by rivers, in marshes and in moss bogs, and very often found with fruit or anthe- ridiophores. It is extremely common especially in X\V. Iceland, and covers banks of streams often in great abundance, to a height of about 300 metres. In S. Iceland it is also very common on damp tuff rocks. This species is most widely distributed in the birch zone to a height of about 300—400 metres above sea-level where it usually grows on marshy or gravelly ground along small streams, or occurs in abun- dance in moss bogs or in marshes among mosses. But it is also met with upon mountain heights, as for instance near Berufjordur, Seydis- fjordur and Isafjordur, where it has been collected abundantly up to a height of 600—700 metres. FAM. ANEUREJE. 10. Aneura pinguis (L.) Dum. Riccardia pinguis (L.) Gr. Very common on damp ground both in marshes and on gravelly soil by rivers and also on damp rocks. It usually grows intermixed in the tufts of other Bryophyta, rarely forming tufts by itself; it has been collected in fruit in a few localities only ^near Eyjafjordur, and near Seljaland at an altitude of about 500 metres . It is most widely distri- buted in the lowlands up to about 300 metres, but it is also frequently met with upon mountain heights. 11. Aneura multifida (Lindb.) Dum. Ricc(ti-(lid miilli/idti (Lindb.) Lindb. Iceland: Lon!, on swampy ground among Sphuynum ruhellunr, W. Iceland: Reykholtdal ! , frequent near hot springs intermixed in the THE BRYOPHYTA Ol ICELAND 405 tufts of other Bryophyta such as Sphagnum rubcllum, Scapania irrigna, and Pcllia Xcesiana. In one place it was growing on a stone which protruded slightly above hot water of a temperature of about 50°; there it was growing intermixed in a tuft of Knthostodon erwetornm, Scapania irrigna and Anthoceros punclatus. This species is recorded by Morch from Iceland, but no speci- mens of it are to be found in the collections. 12. Aneura latifrons Lindb. Riccurdia latifrons Lindb. N. Iceland: several places near Eyjafjordur (O. I). !; Akureyri!; Husavik!. NW. Iceland: Laugarland!. SW. Iceland: Reykjavik!: Kolla- fjordur!. This plant usually grows on peaty soil intermixed in the tufts of other Bryophyta such as Dicranella crispa, Lophozia Kunzeana, Sphagnum spp. and Aneura pingvis. Near Husavik it was growing among Lepto- bryum pyri forme on damp gravelly ground. FAM. METZGERIE^E. I 13. Metzgeria furcata (L.) Lindb. Commonly distributed all over Iceland in dry rock-clefts and on rock-faces, usually associated with Radala complanata. In S. Iceland, where it is very common on rock-sides in clefts of tuff rocks, it is sometimes found also in rather damp localities. Only sterile specimens have been found. Metzgeria furcata is a typical lowland-plant. In Iceland it has not been found at a higher altitude than about 300 metres. FAM. HAPLOL.ENE.E. 14. Pellia Neesiana (Gottsche) Limpr. Marsilia Xcesiana Lindb. Very common on wet ground especially along river-banks, in moss bogs and on inundated ground; somewhat more rare in marshes. It grows almost always intermixed in the tufts of other Bryophyta, and usually as an erect, elongated form among Philonotis, Mniuni cinclidioid.es, Acrocladium cuspidatum, Marchantia, etc., more rarely it grows in un- mixed tufts on damp ground. Fruit appears to be produced rather rarely and also rather sparingly. This species has its main distribution in the lowlands up to about 300—400 metres, and it is only by exception that it has been found above this level. Pellia epiphylla L Lindb. is enumerated in the majority of the 406 A. HESSELBO older lists, and Gronlunds records it from many localities in Iceland, but all the specimens found in the collections under this name are those of Pelliu Xeesiana. 15. Blasia pusilla L. N. Iceland: Reykum (Grl.)!; Melar (Grl.)!; several places near Modru- vellir near Eyjafjordur O. D.) ! ; Reykjalaug in Fnjoskadalur (O. D.)!; Oxnadalur!; Stadr near Hrutafjordur!. W.Iceland: Gilsbakki!; common in Reykholtdalur!. S. Iceland: Reykirdalur!. Only the $ plant has been found in Iceland. This species occurs in rock-clefts and along the banks of streams, on wet gravelly ground, and also on clay near hot springs. For instance, it grows abundantly in Reykholtdalur, and more scantily in Reykir- dalur on the damp, steaming clayey flats, the temperature of which just below the surface is about 25 J -40°; it is found associated with Gymnocolea inflata, Haplozia crcmilata and Fossombronia Dnmoiiieri. On banks of streams it usually grows rather scantily and associated with Dicranella crispa, Pellia Xeesiana, Didijmodon rnbellns, Angstromia longipes, Scapania subalpina, etc. Note. Morchia Biyltii (Morch) Brockm. is recorded by Gronlund to occur in Brynjudalur, but the specimens preserved in the Botanical Museum in Copenhagen belong to Blasia pusilla. FAM. CODONIE.E. 16. Fossombronia Dumortieri (Hub. et Genth) Lindb. N. Iceland: near Mvvatn!. S. Iceland: near hot springs on Rej'- kjanes (Ostf. ! ; Reykir!: Thorlakshver!; Laugarashver!; Sydri Reykjahver!; Thingvellir!; Kolvidarhol!; Geysir Ho.;!). W. Iceland: common near hot springs in Reykholtdalur!. Fossombronia Dumortieri is one of those species which are rarely absent from the neighbourhood of any hot springs if only the water does not contain too much sulphuretted hydrogen. There it grows on warm clayey flats with a temperature of about 40°, and especially on damp slopes along the outlets of springs; as a rule it sets fruit which ripens during June— July. In Reykholtdalur it is common near all the hot springs, also near the springs on Riskupstungur, near Geysir and on Reykjanes. In Reykir- dalur, where the majority of the springs give out abundance of sul- phuretted hydrogen in their vapours it occurred less frequently, but nevertheless was found near several springs, also around some small fumaroles near Kolvidarhol from which issued aqueous vapours im- pregnated with sulphuretted hydrogen. It grows in all these localities associated with other Hepatica?, for instance Gymnocolea inflata, Haplozia crcmilata and Anlhoccros punctatiis. Near Mvvatn it was growing around a fumarole, on a damp clayey flat with a temperature of about 40°, associated with Kicciu bifurca and Haplozia crenulala. The only place THE BRYOPHYI A OF ICELAND 407 where the plant has been found on other than \varni ground is near Thingvellir where it was growing in a ditch along the road to Hrafnagjfi, on clay washed together into a heap; there it had for companions Dicranella crispa, Didymodon rubellus, Encalyx subellipticus and tiny plants of Pohlia, Bnjum, etc. FAM. EPIGONANTHE.E. 17. Gymnomitrium coral lioides Nees. S. Iceland: Thingvellir (Stp.; Grl.;!); Seljaland (Stp.;!). SW. Iceland: Reykjavik (Grl.;!); frequent in Esja!; Hafnarfjordur!. E. Iceland: frequent!. N. Iceland: Akurevri!. */ Occurs rather common!}7, but as a rule, not abundantly in SW., E. and probably also X. Iceland; in NW. Iceland it has not yet been found. It usually grows on the top of blocks of basalt and lava in small greyish cushions, and rarely on the dry gravelly soil of Grzm/?i/a-heaths. On the heath in Seljaland it occurred on blocks of basalt up to a height of about 400 metres; in Esja it has been found up to about 500 metres. Only sterile specimens have been found. 18. Gymnomitrium concinnatum (Ligthf.) Corda. Commonly distributed over the whole of Iceland. u In the lowlands it is especially common in the lava-fields, where it grows both on the top of blocks of rock and in crevices and caves, generally mixed with other Hepaticrc such as Lophozia alpestris, L. qnin- qaedentata and Plcaroclada albescens v. islandica; but it is also frequently met with in clefts mixed with other Bryophyta and creeping over stones. But it has its greatest distribution from about 300 — 400 metres upwards towards the snow-line, where it grows both on more or less damp ground and on rocks either in low, extensive cushions or mixed with other Bryophyta such as Lophozia alpestris, L. ventricosa, Plcuroclada albescens, Dicraimm Blytlii and 1). fiilvellnm , usually also woven into dense cushions of Conostomiim boreale. In NW. Iceland especially, where it is one of the most frequently occurring Bryophyta, it grows on gravelly flats on mountain heights in extensive carpets associated with Anthelia nivalis, Alicnlaria minor, Polij- tricluun sexangulare and the other above-mentioned Bryophyta. Near Seljaland, at about 650 metres, it was growing in great masses on weathered basalt rocks associated with Marsnpella cmarginata, Pohj- trichum sexangulare and Dicrannm Blyttii. Fruit not rare; it ripens, according to altitude, during June— July. 19. Gymnomitrium varians (Lindb.) Schiffner. NW. Iceland: Dyrafjordur! (at an altitude of about 350 metres^ on damp gravelly ground; Reykjaheidi, in a lava-cleft!. Near DVrafjordur it was growing abundantly in low, blackish-brown mats associated with Anthelia niualis and Alicnlaria minor on ground saturated with melting snow. 408 A. HESSELBO 20. Gymnomitrium revolutum (Nees) Phil. XW. Iceland: Sugandafjordur! at an altitude of about 200 metres). It occurred here, on wet gravelly soil upon a slope, scantily among Hypnum callichroum, Dicmmim Starkci, Scapania iiliginosa and Lophozia Floerckei. 21. Marsupella Funckii (W. et M.) Dum. E.Iceland: Hof!, in brownish-black cushions about one cm. high, in rock-clefts associated with Lophozia alpestris and Dicranum Andersoni; Seljaland! (at about 350 metres), on the ground between blocks of basalt and mixed with Marsupella emarginata and Dicranum Blyttii. 22. Marsupella emarginata (Ehrh.) Dum. NW. Iceland: Dyrafjordur on damp rocks at an altitude of about 250 metres!. S. Iceland: Holt! (at about 400 metres), on marshy ground among Hypnum sarmentosum, Oncophorus virens, etc.; Seljaland!, in several places from an altitude of 350 to 650 metres, both on gravelly soil and on rocks. This species is recorded by Morch from Iceland (figured in Flora Danica. tab 1945), and by Gronlund from Thingvellir and Hafnarfjordur. The specimen from Hafnarfjordur has proved to be Anthelia julacea. Morch's specimens are not to be found in the collections. 23. Marsupella aquatica (Lindb.) Schiffner. NW. Iceland: Kaldalon! by the bank of a small lake intermixed in a tuft of Hypnum sarmentosum and H. exannulatum- Isafjordur!, abun- dantly in an almost dried up river, at an altitude of about 250 metres. 24. Alicularia scalaris (Schrader) Gorda. Very common over the whole of Iceland. Alicularia scalaris is one of the most commonly occurring Hepaticse in Iceland, and is of almost equal frequency in the lowlands as in the higher mountainous regions. Fruit is rather common. It grows especially on a somewhat damp substratum, both on rocks and on gravelly ground and also by streams and in bogs, sometimes as pale green or in exposed localities brownish mats, sometimes sprinkled in the tufts of other Bryophyta. On peaty ground it often forms extensive, continuous carpets in company with Pogonatum urni- gerum. On warm clayey flats it also occurs abundantly, and forms together with Haplozia crenulata dense, reddish-brown or pale green mats along the warm water near both sulphurous and alkaline springs. THE BRYOPHYTA OF ICELAND 409 25. Alicularia geoscypha De Not. Nardia minor (Nees) Arnell, AT. haematosticta Lindb. Commonly distributed all over Iceland and, as a rule, fruiting. This species doubtless occurs as frequently in the lowlands as on mountain heights upwards to the limit of plant-growth. It is generally met with on damp gravelly ground associated with other Hepaticas, for instance by streams with Cephalozia bicuspidata, Scapania subalpina, S. curta, Lophozia alpestris and L. Wenzelii, or on damp gravelly ground on rock\f flats with Pohlia gracilis, P. commutata, Aongstroemia longipes and several other species. On mountain heights, especially in NW. Iceland, it generally grows in company with Anthelia Jnratzkana on gra- velly flats irrigated by melting snow. \ar. insecta (Lindb.) K. M. was collected near Isafjordur (at about 300 metres alt.) together with the type. Note. Alicularia compressa (Hooker) Nees is figured in Flora Danica, tab. 1772, fig. 2, and is recorded to have been found near Gronnefjord(?) by Morch, but no specimens of it are to be found in the collections. 26. Eucalyx subellipticus (Lindb.) Breidler. E. Iceland: Berufjordur!; Seydisfjordur!. N. Iceland: Hof near Eyja- fjordur (O. D.) !; Oxnadalur. NW. Iceland: Kaldalon!; Laugarland!; Grun- navik (at about 350 metres alt.); Gnupsdalur!. W. Iceland: Gilsbakki: Esja, several places!; Kolvidarhol!. S. Iceland: Thingvellir, several places!. It has been collected everywhere in fruit. It is no doubt rather common but often overlooked on account of its diminutive size and resemblance in habit to the far more frequently occurring small species of Alicularia and Haplozia, with which it is generally associated. It is usually found on damp gravelly ground, more rarely on damp rocks or in lava-clefts; now and then in unmixed tufts, but generally mixed with Alicularia scalaris and A. geoscypha. Sca- pania curta, Dicranella crispa, Pohlia spp., etc. Near Hof it grew mixed with Haplozia pumila; in Almannagja it occurred in many places at the bottom of clefts or on humus-covered ledges associated with Lophozia alpestris, Alicularia geoscypha and Scapania subalpina. Near Seydisfjordur it occurred creeping over stones by the river and mixed with Haplozia atrouirens. 27. Haplozia crenulata (Sm.) Dum. Nardia crenulata. Near Geysir (Morch; Stp.!); figured in Flora Danica, tab. 1774, fig. 1, uin uliginis Islandiae frequens, A. Morch.'' Common near all the hot springs in Reykholtdalur!, Reykirdalur !, on Biskupstungur!, on Rey- kjanes (Ostf.)!, near Laugarvatn!, in Lundurreykjadalur! and near Myvatn!. It was found also in W. Iceland: Borgarnes!, at several places along the road; Lsekjarmot!, on wet ground in bogs. NW. Iceland: Laugarland!, on boggy ground. The Botany of Iceland. Vol. I, part II. 27 410 A. HESSELBO Haplozia cremilata is in Iceland a decidedly warm-soil species which is hardly absent from any hot spring, whether sulphurous or alkaline. It grows there in abundance on warm clayey flats which have a tem- perature of 20° -35°, near Myvatn even at a temperature of about 40°. It occurs far more rarety on peaty soil, and then only scantily. Curi- ously enough, these habitats, also, are situated in districts where there are hot springs. Near Laugarland, for instance at the edge of the marsh, there is a small spring with lukewarm water, but the heat from it can exert no influence on Haplozia cremilata, nor does the latter occur in the immediate neighbourhood of the spring. This species varies considerably in colour, size, thickness of the cell-walls and as regards the leaf-margin. In the low, reddish-brown forms which grow on warm ground nearest to the hot water the cell- walls are more highly thickened , and are especially distinctly collen- chymatous, while the more vigorous, green forms which grow at some distance from the spring on more boggy ground, among other Bryo- phyta, have thin-walled cells which are indistinctty collenchj^matous. The marginal cells are sometimes large and thick-walled, sometimes scarcely larger than the other leaf-cells and then only slightly thickened; in such cases it may be difficult to distinguish the plant from the forms of Haplozia sphcerocarpa and Alicularia scalaris with which it is often found associated. Under high magnifying powrers the marginal cells will however always be seen to be somewhat papillose, which is never the case in Alicularia. 28. Haplozia sphserocarpa (Hook.) Dutn. S. Iceland: Grafarbakki near a hot spring (F.)!; Thorlakshver among Catharinea undulatal; Sydri Reykjahver among Oligotrichiim hercynicum !; Laugarvatnshver among Sphagnum cymbifoliuml; Isafjordur on a rocky flat '300—400 metres above sea-level)!. All the forms found, which are quite sterile, stand slender and erect among other Bryophyta and must doubtless be referred more particularly to the type. This species, like its companion Oligotrichiim, has a very peculiar distribution in Iceland, having two such widely different areas of distri- bution as the warm clayey flat with a temperature of 25° -30° and the rocky flat. Note. A liverwort is figured in Flora Danica, tab. 2195, under the name Jungermannia pumila; it is recorded to have been found by Morch near Lejra. Lindberg, in his critical revision of the mosses in Flora Danica, refers it to Jungermannia ccespiticia, but the specimens are not to be found in the collections. 29. Haplozia cordifolia (Hook.) Dum. Very common and often fruiting richly. It grows especially on rocks, in or by waterfalls; or submerged in rivers, where it sometimes covers large surfaces of the firm rocky bottom with its blackish-green mats. But it may also be met with on irrigated gravelly ground or in THE BRYOPHYTA OF ICELAND 411 moss bogs associated with species such as Philonotis seriala, Chiloscyphus polyanthos v. frag His and Scapania nndiilata. It is most widely distributed in the lowlands up to a height of about 300 metres, but is also frequently met with up to about 500 metres, for instance in Esja. 30. Haplozia riparia (Tayl.) Dum. Vestmannaey. S. Iceland: Flokastadagil!; Klitnafoss!; Barkarstadr!; Holt!. In all the above-mentioned localities the plant was growing on tuff' and was, as a rule, fruiting. On Vestmannaey it was growing on "Stora Klit," on the surface of dripping tuff-rocks facing north, associated with Hymenostylium curvirostre, Hypniim filicimim and Anomobryum /Hi forme. In S. Iceland it is fairly common in damp ravines on Fljotshlid and below Eyafjall, and grows there partly associated with the above-men- tioned species, partly in company with Fegatella coniea, Preissia commu- tata, Bryum oeiuim, etc. Haplozia riparia is recorded by Gronlund from Brynjudalur and Seydisfjordur, but the specimens from these localities must be referred to Haplozia atrovirens. 31. Haplozia atrovirens (Schl.) Dum. Common on damp rocks, more rare on damp gravelly ground. It occurs sometimes in low, blackish-green cushions, sometimes intermixed in the tufts of other Bryophyta. Male plants and fruiting plants are frequently met with, sometimes in separate tufts, sometimes mixed in the same tuft. Like Haplozia cordi folia it occurs most com- monly to a height of about 300 metres, but is also frequently met with up to about 500 metres. Var. sphcerocarpoidea (De Not.) Mass, has a distri- bution similar to that of the type, and occurs in the same localities as the latter. Both forms pass evenly into each other. The cuticle of the leaves, in the majority of the plants, is more or less distinctly rough with strife, and rarely smooth. 32. Haplozia pumila (With.) Dum. N.Iceland: Hof, near Eyjafjordur (O. D.)!. It was growing there intermixed in a tuft of Eucalyx siibellipticus. The rest of the specimens referred by Gronlund and Jensen to this species all belong to Haplozia atrovirens. 33. Jamesoniella autumnalis (De Cand.) Steph. S. Iceland: Nuphlidarhals (Stp.)!. 34. Sphenolobus minutus (Crantz) Steph. SE. Iceland: Lon, scantily among Sphagnum mbellam and Fissidens osmiuidoides. NW. Iceland: Hesteyri, in a tuft of Dicramim elongatam. W.Iceland: Grund in Skorradalur. among Polytrichnm strictum. 27* 412 A. HESSELBO This plant was first found by Morch and figured in Flora Danica, tab. 2190, without a more precise notification of its habitat. Gronlund's record of the occurrence of this species in Esja is due to an erroneous determination. 35. Sphenolobus saxicola (Schrad.) Steph. "in Islandia leg Morch" (M. B. H.)!. Figured in Flora Danica, tab. 2693, fig. 1, but no habitat is given. 36. Sphenolobus politus (Nees) Steph. Isafjordur! c. coles. It was growing there in several localities at an altitude of about 200 -300 metres, sometimes along the banks of streams associated with Har- panthus Flotowianus, sometimes in bogs associated with Sphagnum teres, Lophozia quinquedentata and L. Kunzeana. 37.Lophozia quinquedentata (Huds.) Cogniaux. Very common all over Iceland. Lophozia quinquedentata is doubtless the liverwort of most fre- quent occurrence. It is met with, up to the snow-line, in all possible localities which are somewhat damp, now and then in unmixed tufts, but general!}7 woven into the tufts of mosses. Female plants and fruit are rather rare, male plants are far more frequent; plants bearing gemmae are also often met with. It varies extremely as regards size, habit and leaf-form. The extreme members of the variation-series are the large var. turgida Lindb. which is common on boggy ground and t e delicate, often only one mm. broad, var. tenera C. Jens, which is frequent in dry localities, as for in- stance on humus-covered rocks and in lava-fields. 38. Lophozia lycopodioides (Wallr.) Cogniaux. Almost as common as the preceding species on drier ground. It is found especially on stony or grass-covered slopes, creeping over humus-covered rocks, in birch coppices, and on the top of knolls in bogs, sometimes in large, unmixed, yellowish-green tufts, sometimes inter- mixed with other Bryophyta. Only sterile specimens have been found. It varies considerably in size. Delicate forms (var. parvifolia), often only one mm. broad, grow on dry rocks woven into the tufts of other Bryophyta, while the large, vigorous forms are especially met with on slopes overgrown with Hylocomium. Now and then forms also occur which approach very closely to Lophozia Hatscheri (Evans) Steph. But plants which can with certainty be referred to this species have not been found in Iceland. Lophozia lycopodioides is most widely distributed in the birch-zone, up to about 400 metres above sea-level, and is especially wide-spread towards the north-west while it occurs more sparingh7 in S. Iceland. THE BRYOPHYTA OF ICELAND 413 In the district around Isafjordur it is also met with abundantly on the rocky flat, 500—600 metres above sea-level, and near Akureyri it was collected, although sparingly, near the snow-line (at about 770 metres alt.). 39. Lophozia Floerckei (W. et M.) Schiffner. XW. Iceland: Dyrafjordur; Isafjordur; Hesteyri!; Grunnavik!; Kal- dalon!; Arngerdareyri!. SW. Iceland: Svinahraun!. In the majority of the older lists of Bryophyta from Iceland L, Floerckei is recorded from rather a considerable number of habitats, but all the specimens from these habitats preserved in the Botanical Museum in Copenhagen, have been wrongly determined; the majority of them must be referred to Lophozia lycopodioides. The only specimen in the collections, correctly determined, was gathered by Morch, but no habitat is given. This species has a very peculiar distribution as it is very common in the north-west, and is also found abundantlv on the highlv situated v cj «> Svinahraun in the south-west (about 300 metres), but has not otherwise been found in Iceland. In NW. Iceland it ascends from the low land to the rocky flat, but is most frequently met with from 200 to 400 metres above sea-level. There it grows on fairly dry ground in bil- berry heaths, both on the ground and creeping over rocky blocks, as- sociated with Dicranum fuscescens, D. scopariiim, D. molle, Lophozia lyco- podioides and L. quinquedentata. At a higher level it grows especially on the Salix-herbacea-flats, associated with Lophozia ventriosa, L. alpestris, Dicranum Starkei, Plenroclada albescens, etc., but also occurs on a more damp bottom. In Svinahraun it occurred commonly between the lava-blocks and %/ also in a damp depression at the edge of the lava-field, associated with Polytrichum commune. 40. Lophozia quadriloba (Lindb.) Evans. E. Iceland: Berufjordur!; Lon!; common near Seydisfjordur; Val- lanes!. X. Iceland: Husavik!; Akureyri!; about Eyjafjordur (O. D.;!). NW. Iceland: Kaldalon!; Isafjordur!. W. Iceland : Melar (Grl.)!; Esja, several places!. S.Iceland: Svinahraun!; Holt!; Hornafjordur!. The Vestmanna- eyjar !. This plant is no doubt common, but usually it occurs so scantily that it is only found by close search of the Bryophyte collections under the microscope. It grows both on damp humus-covered rocks and on boggy ground, from the low land upwards to the mountain-tops. Thus, near Isafjordur it was collected at about 440 metres. Near Seydisfjordur it is frequent up to about 500 metres and near Akureyri it was found on cliffs at an altitude of 900 metres. Lophozia quadriloba hardly occurs in unmixed tufts, but always mixed with other species, for instance with Dicranum spp. or on rocks among Distichium montanum, Tortella fragilis, Oncophorus, or with other Hepaticae such as Cephalozia, Lophozia alpestris and Aneura pinguis. On 414 A. HESSELBO boggy ground it is found interwoven with Hypnacece in their tufts, but rarely in those of Cinclidium, Lophozia Kunzeana or other bog-mosses. The majority of the specimens investigated are small and delicate, and must partly be referred to forma heterophylla Bryhn et Kaalaas, and partly to forms transitional between this and the type. Only sterile plants have been found. 41. Lophozia Kunzeana (Hub.) Evans. Very common in bogs, on damp rocks, damp gravelly ground, etc. It is most widely distributed in bogs where it grows woven into, or creeping over tufts of other Bryophyta, especially Sphagnum. Near Akureyri, for instance, it commonly occurs in bogs up to a height of about 600 metres. In S. Iceland it is rather rare in the bogs of the lowlands, but is met with abundantly at an altitude of 200—400 metres. 42. Lophozia barbata (Schmid.) Dum. E. Iceland: Arbser, among Grimmia canescens (H. J.)!. W. Iceland: Bjarnarhofn (H. J.)!; Berserkjahraun (H. J.)!; Reynivellir (Grl.)!; Nordre- dalur in the district of Borgarfjordur!; Alafoss!. In addition to the above-mentioned localities Gronlund and Helgi Jonsson record this species from several other localities, but some of the specimens which have been investigated proved to be wrongly deter- mined (being, as a rule, forms of L. lycopodioides), so only those loca- lities are enumerated here from which authentic specimens are known. L. barbata appears to be rather rare. It has as a rule been col- lected, intermixed rather sparingly in tufts of other Bryophyta especially Grimmia and Hylocomium spp. and belongs to the Grzmmza-heaths or to the mossy bottoms of birch coppices; thus in Nordredal it frequently occurred in birch coppices among Hylocomium spp., Dicranum scoparinm, Ptilidium ciliare, etc. Note. Lophozia gracilis (Schl.) Stephani is recorded from several localities, but all the specimens which have been investigated have been wrongly determined, being mostly Lophozia lycopodioides var. parvifolia. 43. Lophozia ventricosa Dicks.) Dum. Common on more or less damp ground, both boggy and gravelly ground, and on rocks on mountain heights. This species is very common especially in NW. Iceland, and occurs there on a heathy bottom woven into tufts of Dicranum ; along the banks of streams associated with Harpanthus , Lophozia quinqiiedentata and Cephalozia bicuspidatct] and in bogs among Spagnum. It appears, on the whole, to be more frequent the higher it ascends; undoubtedly its main distribution is from a height of about 300—400 metres upwards. Var. porphyroleuca (Nees) Hartm. is likewise commonly distributed and occurs, for instance, frequently interwoven with Conostomum in its compact tufts, and also in tufts of Dicranum and Sphagnum on damp ground. THE BRYOPHYTA OF ICELAND 415 It is hardly possible to draw any distinct boundary line between this form and the type, the thickenings of the leaf-cells showing all transitional stages from quite thin-walled to decidedly collenchymatous cells, and the colour also varying according to the habitat. Fruit is rare; gemmae are as a rule present. Var. confertifolia (Schiffn.) syn. Lophozia confertifolia Schiffner. Plants agreeing exactly with the description of this form and with the figure in Rabenhorst's Kryptogamenflora, fig. 314, occur rather commonly on damp gravelly soil in N\V. Iceland associated with all the transitional forms of L. uentricosa; I think they can only be regarded as Alpine forms of the present species. 44. Lophozia Wenzelii (Nees) Steph. E. Iceland: Seydisfjordur !; Vallanes!. N. Iceland: Tvera in Oxnadalur!. NW. Iceland: Isafjordur, (at about 200 metres alt.)!. SW. Iceland: Svi- naskard (at about 400 metres alt.). It grows on wet gravelly soil or peat, especially along streams where it forms low, dense carpets or grows mixed with Aliciilarict sca- laris, Dicranella crispa, Distichium inclinatnm and other Bryophyta. Near Isafjordur it was growing by a small stream together with Sphagnum squarrosum. 45. Lophozia alpestris (Schleich.) Evans. Very common all over Iceland. It generally grows woven into tufts of other Bryophyta, but now and then forms tufts by itself. It is found on almost every kind of substratum, from the sea-level to mountain heights. It occurs most fre- quently on rocks, especially those which are somewhat damp, but is also met with on damp ground along the bank of streams, on the gra- velly flats of mountain heights, in lava-clefts and woven into the moss- carpets of Grzmmza-heaths. Fruit and calyces occur rarelv and have been found onlv in X\V. \j */ *f Iceland: Gnupsdal! and in S. Iceland: Seljaland (at about 350 metres !; Svinahraun!. Male plants are rather common, and gemmae are very often present. 46. Lophozia excisa (Dicks.) Dum. S. Iceland: Reykir!; fr. It grows there on damp gravelly soil by a small stream associated with Eucalyx sub elliptic as, Scapania cnrta and Dicranella crispa. This species is recorded from Iceland by Morch, but of the two specimens found in the collection in the Botanical Museum in Copen- hagen under this name, one is Lophozia ventricosa var. porphgroleuca and the other L. heterocolpos. Note. Lophozia bicrenata (Schmid.) Dum. is recorded to have been found near Krisuvik by Steenstrup, but the packet contained only a mixture of several other species of Lophozia. 416 A. HESSELBO 47. Lophozia Schultzii (Nees) Schiffner. E. Iceland: SeydisfjOrdur; Vestdalur (at an altitude of about 200 metres)!. N. Iceland: Akureyri!. W. Iceland: Stykkisholmur!. It was collected everywhere only in small quantities together with bog -mosses such as Hypmim revolvens, H. stellatum, Mnium Seligeri, etc.; it was as a rule sterile. Near Stykkisholm it was collected in unmixed tufts with antheridia and young calyces. 48. Lophozia Mulleri (Nees) Dum. Common, but occurred almost always in small quantities inter- mixed in tufts of mosses. This species is most frequent in the lowlands up to about 300-400 metres above sea-level, but it also occurs at great altitudes in the Alpine region, for instance, at about 600 metres on Berufjordurskard. It is almost always sterile. Lophozia Miilleri occurs on very different substrata, most frequently on rocks, but it may also be found on damp ground along streams, or even in bogs. It varies exceedingly in size according to the degree of dampness of the habitat. Xerophilous forms from rocks are usually small and delicate, while bog forms which grow in the tufts of Hypnacece are considerably larger and often approach so closely to L. Hornschu- chiana that they are difficult to distinguish from the latter. On the damp, vertical sides of the clefts of the tuff rocks of S. Iceland, for instance on Fljotshlid, a vigorous, blackish-green form is frequently met with forming large, pure mats. 49. Lophozia Hornschuchiana (Nees) Macoun. Jangermannia bantryensis, Hooker. E. Iceland: Seydisfjordur, frequent up to about 400 metres!. N.Ice- land: Akureyri!; Hof; Eyjafjordur (O. D.)! c. coles. NW. Iceland: Isa- fjordur. W. Iceland: Dalsnrynne in Nordredal!; Mulakot!; Botnsdalur!; Reykjavik!; Kollafjordur. Occurs rather frequently, but as a rule scantily, on boggy ground among mosses (Hypnum, Sphagnum, etc.), more rarely on stones in rivers. In Nordredal, for instance, it was found abundantly in a small river on submerged stones. 50. Lophozia heterocolpos (Thed.) Howe. N. Iceland: Sponsgerde near Eyjafjordur (0. D.)!. NW. Iceland: Baeir!; Kaldalon!. SW. Iceland: Hafnarfjordur!; Esja!, at an altitude of about 400 metres; Thingvellir (Grl.;!). In all the above localities it was found on humus-covered rocks, especially in clefts. Near Kaldalon it grew on damp rocks woven into a tuft of Meesea trichoides and Dicranella siibulata; on Esja it grew upon damp tuff- rocks. In Thingvallahraun it is widely distributed in clefts THE BRYOPHYTA OF ICELAND 417 and caves in the lava-fields, usually mixed with Blepharostoma tricho- phyllum, Amblystegium Sprucei, Dip lop hy Hum albicans and Plagiothecium denticiilatum. The characteristic gemmiferous shoots occur always, but plants in fruit have not been collected. 51. Gymnocolea inflata (Huds.) Dum. "In Islandia" leg. Morch! and figured in Flora Danica, tab. 1945, fig. 2; SW. Iceland: Krisuvik (Stp.)!; Laugarvatn (Stp.!); Reykholt Grl.;!); Reykirdalur!; Kolvidarhol!. NW. Iceland: Laugarland!. Gronlund records this species from several other localities be- sides those mentioned above, but the specimens in the Botanical Museum in Copenhagen are all wrongly determined and must be referred to Lophozia Miilleri or to L. alpestris. In Iceland Gymnocolea inflata is a decidedly warm-soil plant which, with the exception of a single locality, was found exclusively on the steaming clayey flats around hot springs in SW. Iceland. Near Laugar- land it was growing rather sparingly in a bog. Haplozia cremilata was growing in its neighbourhood, and as there was a small spring with lukewarm water at the edge of the bog it is possible that the occur- rence of the two species is connected with the spring, although there was no characteristic vegetation around the spring, but only the com- mon bog-plants. In Reykirdalur, where it is found in abundance near almost all the hot springs, it forms extensive brownish-black or almost entirely black mats on warm ground with a temperature of as much as 40° around fumaroles or on slopes stretching down towards the boiling hot basins. At some distance from the spring it will grow woven into the tufts of Polytrichum commune or mixed with Cephalozia bicuspidata which likewise occurs in brownish-black forms. It was collected with calyces only at Laugarvatnshver. 52. Plagiochila asplenioides (L.) Dum. Very common everywhere. Plagiochila asplenioides occurs on almost every substratum, on damp or on dry rocks, in bogs, on earth, etc. It is most frequent up to a height of about 300 metres above sea-level, but often occurs as far up- wards as about 600—700 metres. Usually it grows intermixed in the tufts of other Bryophyta, more rarely it forms tufts by itself. The majority of the specimens which have been collected are small, only 1—2 mm. broad, with leaves slightly dentate or entire. Larger forms with leaves typically dentate occur mostly on somewhat damp ground, for instance among stones on a talus of loose blocks and debris (Urd) or in caves. Only sterile specimens have been found. 53. Leptoscyphus anomalus (Hook.) Lindb. E. Iceland: Stod (H.J.)!. 418 A. HESSELBO 54. Lophocolea cuspidata Limpr. Vestmannaey!. S. Iceland: Holt!. On Vestmannaey it was found in several places at the base of cliffs and in specially large quantities in Heljusdal where it grew abundantly among stones on an Urd usually mixed with Eurynchium , Stockesii and Mnium undiilatum. Near Holt it was found in several places, but everywhere only in small quantities in clefts of tuff-rocks, woven into the tufts of mosses. Only sterile specimens have been found. 55. Lophocolea minor Nees. N. Iceland: Halsskogur (O. D.)!. S. Iceland: Reykirdalur!; Vestman- naey: Heljusdal!. In Reykirdalur it was growing rather sparingly on a grass-covered slope stretching down towards a stream. On Vestmannaey it occurred in several places associated with L. cuspidata sometimes intermixed in its tufts. In all the localities only sterile specimens were collected, but bearing the characteristic gemmae. 56. Chiloscyphus polyanthus (L.) Corda. Common in wet localities or in water, on gravelly ground and occasionally in bogs and on wet rocks. Only sterile specimens were found. It occurs sometimes in unmixed cushions, which are usually blackish- green in colour in water and yellowish-green in boggy ground, some- times mixed with other Bryophyta such as Marchantia, Philonotis, Dicra- nella squarrosa and Mnium spp. It is most widely distributed in the lowlands up to about 300 metres and does not appear to ascend much higher than 400 metres. The typical form was collected only in S. Iceland on damp tuff- rocks near Holt. All the other plants which have been investigated be- long to var. fragilis (Roth) K. M. It varies considerably as regards size and colour, but the form of the leaves and the size of the leaf- cells are almost always the same. Note. Chiloscyphus pallescens is recorded from several places by Morch, Gronlund and HelgiJonsson, but all the specimens refer- red to this species belong to Chiloscyphus polyanthos var. fragilis. 57. Harpanthus Flotowianus Nees. E. Iceland: Seydisfjordur, several places!. N. Iceland: several places around Eyjafjordur (O. D.)!; Stadr near Hrutafjordur!. NW. Iceland: Dyra- fjordur; Sugandafjordur; Isafjordur; Grunnavik; Kaldalon; Arngerdareyri!. W. Iceland: Olafsdalur in Dalasysla (H. J.)!; Esja, several places!. In NW. Iceland this species is of the most frequent occurrence among all the Bryophyta and is met with everywhere on wet ground up to a height of about 300 metres above sea-level. In the other parts of the country it is wanting or rare; on Esja it is however rather fre- THE BRYOPHYTA OF ICELAND 419 quent. It occurs both in hogs and along the banks of streams, and also on inundated gravelly ground, usually intermixed in tufts of mosses such as Cinclidiam, Mnium cinclidioides, Sphagnum and Hypmim spp. ; also on wet gravelly soil associated with Lophozia qiiiiujuedcnlata, Ce- phalozia bicuspidata and other Hepaticse. Only sterile specimens have been found. FAM. TRIGONANTHK.K. 58. Cephalozia bicuspidata (L.) Bum. Very common on earth, damp gravelly soil, humus-covered rocks, and in bogs up to a height of about 600 metres above sea-level, espe- cially in NW., N. and in parts also of E. Iceland, while it appears to be more rare in S. Iceland. It grows partly in large cushions, for instance on damp ground by streams, partly intermixed in tufts of mosses especially Sphagnum and Dicramim spp. and thrives best on a somewhat damp substratum. Found as a rule in fruit. It varies con- siderably as regards size and colour. Var. Lammersiana (Hub.) Breidler grows on very wet ground , for instance along banks of streams, where it forms large green mats in association with other Hepaticse. It is especially common in N\V. Ice- land. The bog-forms, which grow erect among Sphagnum, are slender with spreading leaves. On damp slopes a dark-brown-to-black form frequently occurs, often forming very extensive carpets; it corresponds most closely with var. Loeskeana (Schiffner) K. M., in previous lists it was referred to var. Lammersiana. At the head of deep lava-caves and at the bottom of lava clefts it occurs in association with Alicularia scalaris as much elongated shade-forms. Note. Cephalozia Francisci is recorded by Morch from Hafnar- fjordur, but the specimen in the Botanical Museum is C. bicuspidata. 59. Cephalozia ambigua C. Mass. NW. Iceland: Laugarland, fr. !. It grew there in small brownish tufts on the damp ground at the bottom of the vallev. v • 60. Cephalozia pleniceps (Aust.) Lindb. Common in all parts of Iceland except in the southern part, where it appears to be rare. It is especially common in NW. Iceland and forms there one of the most frequently occurring Hepaticse. It occurs especially on damp ground and in bogs, woven into tufts of Sphagnum, Dicramim and Mnium hornum or associated with Lophozia Kunzeana, L. quinqiiedenlata and other Hepaticas and as a rule bears calyces or fruit. It occurs most frequently up to a height of about 300 metres, but it is also often met with at far greater altitudes. Var. macrantha (Kaalaas et Nichols.) K. M. is widely distributed on wet ground, and grows in association with similarly elongated forms of 420 A. HESSELBO C. bicuspidata and Cephaloziella Hampeana, woven into the tufts of Sphagnum spp., but is as a rule sterile. Note. Cephalozia connivens is recorded by Morch and Gronlund as found in Iceland, but all the specimens which have been investigated belong to C. pleniceps. 61. Cephalozia media Lindb. N. Iceland: Arnarfellsaurar (St.;!); NW. Iceland: Grunnavik!, inter- mixed in tufts of Dicranum fuscescens. 62. Pleuroclada albescens (Hook.) Spruce. E. Iceland: Seydisfjordur!, common above a height of about 400 metres N. Iceland: Akureyri!, common above 500 metres; Hestahraun (St.)!. NW. Iceland: Very common above 300 metres!. Var. islandica (Nees) Spruce. N. Iceland: Reykjaheidi!. S. Iceland: Thingvallahraun ^Morch; Stp. ; Grl.;!); Hafnarfjordur !. The typical form is no doubt common on mountain heights, at any rate in N., NW., and E. Iceland. In S. Iceland it has not yet been found. On mountain heights it grows on stony flats associated with Dicranum spp. (D. Starkei, D. molle and D. fuscescens), Lophozia spp. and Cesia conclnnata or associated with Polytrichum sexangulare, Lophozia ventricosa, Cesia concinnata, etc., on Salix-herbacea-Rats. The variety belongs especially to the lava-fields and grows there at the bottom of deep clefts, creeping over blocks of lava, often in abundance. It occurs there either in large whitish-green cushions or mixed with Hylocomium spp., Rhacomitrium hypnoides, Polytrichum alpinum, P. sexangulare, Lophozia spp., etc. Only sterile specimens of each form have been found. 63. Cephaloziella Hampeana (Nees) Schiffn. \7ery common, but occurs only as scattered shoots intermixed in the tufts of mosses, sometimes, however, also in tiny, yellowish-green, brownish or reddish tufts upon these. It occurs on highly different substrata. On rocks and on earth it grows in tufts of Dicranum spp., Ditrichum flexicaule, Distichium montannm, Tortella fragilis, etc.; in bogs it has been found woven into tufts of Sphagnum, Sphaerocephalus palustris, Hypnacece, Oncophorus spp. and several others. Bog- forms, with elongated stems and widely spreading, very much projecting leaves, agreeing most closely with var. erosa Warnst., occur very commonly in Sphagnum cushions. The leaf-tissue varies very considerably, the leaf-cells, even on the same plant, being sometimes quite thin-walled, sometimes more or less thickened; the leaves also are more or less outspread, so that all pos- sible transitional forms between this species and Cephaloziella rubella are known. THE BRYOPHYTA OF ICELAND 421 64. Cephaloziella rubella (Nees.) Warnst. Typical specimens of this species were collected in the following localities: S.Iceland: Hornafjordur!. E. Iceland: Seydisfjordur!. X. Iceland: Hafrardalur (St.)!; Akureyri!, at an altitude of about 500 metres!; Hof (O. D.!). SW. Iceland: Kollafjordur!. S. Iceland: Holt!. It was found everywhere woven into tufts of Sphagnum spp. and Dicranum spp. (D. fuscescens and D. angiistum] and usually mixed with Cephalozia bicuspidala and Lophozia spp., now and then also with C. Hampeana. Near Isafjordur it grew sparing!}' in a tuft of Mnium hornum, which was densely interwoven with Cephalozia pleniceps. It was col- lected everywhere in fruit. C. rubella is an uncertain species which when sterile is in many cases hardly distinguishable from C. Hampeana. C. dwaricata and C. bifida are recorded from several places in Ice- land, but the specimens belong either to C. Hampeana or to C. rubella. Gronlund's C. dwaricata from Melar is Lophozia quadriloba. 65. Odontoschisma Sphagni (Dicks.) Dum. W. Iceland: Snaeldubeinstadahver in Reykholtdalur!. It was found in the above locality in small quantity woven into a tuft of Sphagnum rubellum on a warm substratum. This species is recorded from Iceland in several old lists and is figured in Flora Danica, tab. 2251 (leg. Morch), but all the specimens found in the collections under this name are those of 0. elongatum. 66 Odontoschisma elongatum (Lindb.) Evans. "In Islandia" (Morch!). E. Iceland: Hof!; Lon!; frequent near Sey- disfjordur!. X. Iceland: Hvarf (St.)!; Akureyri!. \V. Iceland: Budahraun (H.J.)!; Grund in Skorradalur!; common around Reykjavik!. S. Iceland: Holt! at an altitude of about 400 metres. It grows usually woven into tufts of bog mosses such as Sphagnum, Hypnum and Oncophorus spp., Meesia trichoides, Lophozia Kunzeana, more rarely upon moss-tufts or on wet ground, in small brownish tufts. Only sterile specimens have been found. A specimen collected by Morch, having tiny, inconspicuous under- leaves and less thickened cell-walls bearing fine warts, forms a transi- tional form to 0. Sphagni. 67. Odontoschisma denudatum (Mart.) Dum. W. Iceland: Braudarholt near Reykjavik! JV It grew in the above locality on boggy ground among other Bryo- phyta. 422 A. HESSELBO 68. Odontoschisma Macouni (Aust.) Underwood. S. Iceland: Bergarfoss near Hornafjordur!; E. Iceland: Grottafoss near Seydisfjordur ! at an altitude of about 200 metres. N. Iceland: Hof (O. D.)!. SW. Iceland: Svinahraun!. This plant grows partly in small unmixed tufts, partly mixed with other Bryophyta such as Anoectanginm lapponicum, Distichinm montanum, Pohlia crnda, Blepharostoma trichophyllum on damp humus-covered rocks. In Svinahraun it grew in lava-clefts filled with humus. 69. Calypogeia Trichomanis (L.) Corda. N. Iceland: near Mvvatn (Grl.!); Reykjahlid!. W. Iceland: near se- veral hot springs in Reykholtdalur!; Tunguhver (probably Deildatungu- hver) (Grl.;!); Kollafjordur!. S. Iceland: Laugarashver!; Geysir!. More- over, Gronlund records this species from Hvammur, but no specimens of it are to be found in the collections. The plant grows in all the above localities on a warm substratum. Near Reykjahlid it covered the roof of a lava-cave which had a tem- perature of about 25°. In the other localities it occurred on a warm damp substratum woven into mosses such as Sphagnum, Hypna and Polgtrichu.ni, or in pale green to brownish cushions above them. In Reykholtdalur where it occurred abundantly in several localities, the temperature in the tufts was from 25° to 27°. 70. Lepidozia setacea (Web.) Mitten. S. Iceland: Merkjafoss (Feddersen)!. It was found very sparingly in the above locality associated with Cephalozia pleniceps and woven into a tuft of Dicranam scoparinm. FAM. PTILIDIOIDE.E. 71. Blepharostoma trichophyllum (L.) Dum. Very common from the lowlands up to about 500—600 metres above sea-level. This species rarely forms unmixed tufts, but grows almost always woven into tufts of other species and is met with in the most varied localities, on boggy ground and damp gravelly ground along rivers, in lava-fields, on damp rocks, and especially in abundance in rock-caves where it often covers the roof and walls in association with Ambly- stegium Sprucei, with a thin dark-green layer. Fruit occurs rather rarely; but it is found plentifully in Alman- nagja!, and near Hof in N. Iceland (0. D.)!. \ 72. Chandonanthus setiformis (Ehrh.) Lindb. In the herbarium of the Botanical Museum there is a specimen, labelled by Morch "In Islandia, among Trichostomum cancscens, Aug. 1820." THE BRYOPHYTA OF ICELAND 423 73. Anthelia julacea (L.) Duni. Common in the lowlands on damp gravelly ground and creeping over wet stones in streams, occasionally also on damp boggy soil; fruit is not rare. It does not appear to ascend higher than about 400 me- tres above sea-level. 74. Anthelia Juratzkana (Limpr.) Trevis. Anthelia nivalis (Sw.) Limpr. ex. p. Very common on damp gravelly flats irrigated by melting snow, somewhat rarer on damp gravelly ground along streams or on damp rocks. This plant has its main distribution on mountain heights where, on the clayey or gravelly flats next to the snow-covered areas, it forms large, continuous carpets of a peculiar bluish-black colour, often mixed with Salix herbacea or with other Bryophyta such as Alicularia geo- scypha. Lophozia ventricosa and Polytrichum sexangnlare. In NW. Ice- land, where the snow on slopes with a northern exposure may remain during the greater part of the summer, these Anthelieta often descend to sea-level. The plants growing on damp rocks or gravelly ground in lower levels differ from the typical form from mountain heights in being lighter in colour, usually yellowish green, and in the tufts being as a rule higher, with less close-set leaves; or it may also grow intermixed with other Bryophyta especially HepaticaB. A. Juratzkana and A. nivalis are so closely related that in many cases it is impossible to determine them when sterile. While the typi- cal A. Juratzkana, as it occurs in abundance on mountain heights, is very characteristic because of its extensive low carpets, quite typical specimens of A. julacea are far more rarely met with on the damp soil of the lowlands. Of far more frequent occurrence are forms which pass, more or less, in habit, size of leaf-cells and thickness of cell-walls from A. julacea towards A. Juratzkana. 75. Ptilidium ciliare (L.) Hampe. Very common both on dry and on somewhat damp ground. The plant grows both among Hylocomium spp. on slopes and inter- mixed in heaths of Rhacomitriam hypnoides and R. canescens on more or less damp rocks coated with soil, and also in clefts in lava-fields and on knolls in bogs. It occurs most frequently in low-lying regions up to about 300—400 metres, but may also occasionally be met with on mountain heights. Only sterile specimens have been found. FAM. SCAPANIOIDE.E. 76. Diplophyllum albicans (L.) Dum. "In Islandia" (Morch!). W. Iceland: Budahraun H.J.)!; Hafnarfjordur (Grl.; H.J.;!); Svinahraun!; Modruvellir in Kjos!. S. Iceland : Thingvalla- 424 A. HESSELBO hraun (Grl.; Stp.;!); Krisuvik (Stp.)!; Holt!; Reykirdalur!, at an altitude of about 260 metres. Diplophyllum albicans is a plant characteristic of the lava-fields of West and South Iceland and occurs there in great abundance on ver- tical rock-sides in clefts and caves, while it appears to be entirely ab- sent from the lava-fields of North Iceland. Outside the lava-fields it has been gathered only extremely sparingly among stones on heaps of debris at foot of cliffs (Urd). In Reykirdalur it grew scantily on a warm substratum among large blocks of basalt. Only sterile specimens have been found. 77. Diplophyllum obtusifolium (Hook.) Dum. "In Islandiae montibus leg. Morch" and figured in Flora Danica, tab. 1831, fig. 2. No specimens of it are to be found in the herbarium of the Botanical Museum. In the district of Seydisfjordur!, on a damp rock-face by the river it occurred in a small quantity in a tuft of Di- cranum molle and Lophozia Kunzeana. In N. Iceland: Asbyrgi!, it was found on the ground among fallen blocks of lava. Only sterile specimens have been found. 78. Scapania subalpina N. ab Es. Common on damp ground along streams, on damp rocks, in clefts and on damp slopes of the low land. It does not appear to ascend much higher than about 300 metres. tf plants are very common; catyces and fruit occur occasionally. The plant varies in having deeply toothed to almost entire leaves. It is usually green or vellowish-green in colour, but sometimes reddish */ O *J CJ or brownish to almost blackish-brown in more exposed localities. 79. Scapania remota Kaalaas. N. Iceland: Akureyri!. The plant, which agreed exactly with the description and figure irr Karl M tiller's Monographic der Lebermoosgattung Scapania, grew in the above locality, in a bog 400 metres above sea-level, intermixed in tufts of Oncophorus virens. 80. Scapania irrigua (Nees) Dum. Very common on damp ground, in bogs, along streams and on damp rocks. This species is most widely distributed in the lowlands up to about 300 metres above sea level, but may also frequently be met with at high altitudes in the Alpine regions. In wet localities, especially in bogs, where it occurs everywhere woven into the tufts of other Bryophyta, it is usually yellowish green in colour. The leaves are en- tire or fewly toothed towards the apex with thin-walled or slightly collenchymatous cells. But occasional!}7 vigorous, brownish-green forms THE BRYOPHYTA OF ICELAND 425 also occur with more highly thickened cell-walls. In somewhat drier localities it is usually brownish in colour and more compact with more deeply toothed leaf margins, sometimes almost as in S. siibalpina and with more thick-walled cells. Small forms from damp sandy soil often constitute transitional stages to S. curta, while vigorous aquatic forms approach closely to S. undiilata. A very vigorous form with leaves which were as deeply toothed as in S. siibalpina was found in abun- dance in lava-clefts near Thingvellir. J* plants are common ; calyces and fruit occur rather rarely. Note. Scapania compacta is recorded by Gronlund from Esja, but the specimen in the Botanical Museum is really Scapania irriaua. 81. Scapania uliginosa (Sw.) Dum. E. Iceland: Stod (H. J.)!. NW. Iceland: Gnupsdal in Dvrafjordur!: Sugandafjordur ! ; Isafjardarheidi!; Dynjandi!; Arngerdareyri. With the exception of a single localitj^ in E. Iceland this species was found only in NW. Iceland where it is rather common on very wet or irrigated soil along streams, often occurring in great abundance up to a height of about 400 metres. Near Arngerdareyri it grew abun- dantly in a bog in reddish-brown tufts associated with Hypmim spp. The leaf-form and habit in this form were typical, but the leaf-cells had brownish and rather thickened walls and a roughly granular cuticle. The plant from Sugandafjordur differed from the type in its leaves being sometimes distantly toothed and the cells very slightly thickened at the angles, in which respects it approached S. irrigna. 82. Scapania paludosa C. M. NW. Iceland: Gnupsdal in the district of Dvrafjordur, c. coles.! Grun- navik <$ \ ; Isafjordur JM. In Gnupsdal the plant grew abundantly in the water in small streams, where it formed large, loose, green to brownish mats. The leaves were highly decurrent, with indistinct teeth or entire margins, and thin-walled cells. Near Isafjordur and Grunnavik it grew on wet boggy ground. The leaves in both these forms were shortly decurrent and more or less toothed with a broadly reniform or (often in the same plant) cordate postical lobe which was occasionally furnished with a small point as in S. irrigua; the leaf- margin was often reflexed as in S. iindulata; the cells were thin-walled, but towards the margin occasionally somewhat thick-walled. The commissure is typically short and strongly curved with broad wings. 83. Scapania dentata Dum. Scapania purpurasccns (Hook.) Pearson. E. Iceland : Berufjordur!; Seydisfjordur!. common up to about 400 metres. Kirkjubol (H. J.) !. N. Iceland: StoraGja!. YV. Iceland: Hvammur The Botany of Iceland. Vol. I, part II. 28 426 A. HESSELBO (Grl.)!; Esja!. common up to about 400 metres above sea-level; Hafnar- fjordur!. S. Iceland: Krisuvik (Stp.)!; Krokr (H. J.)!; Almannagja!; Holt!; Seljaland!; Austerhlid near Geysir!. This species has its main distribution in E. and SW. Iceland and it has not been found in NW. Iceland. It grows especially on wet rocks and often in the water itself, but also on gravelly soil along the margin of streams. Thus, near Seydisfjordur it occurred abundantly along several rivers. In such localities it forms extensive reddish brown cushions several centimetres deep. On damp soil and on rocks it forms low cushions, green, rose-red or reddish-brown in colour. In the lava-fields near Hafnarfjordur and Thingvellir and in Stora Gja it usually grew at the bottom of the com- paratively dry caves and clefts in small, flat tufts of a peculiar yellowish-green or beautiful rose-red colour. Such forms from com- paratively dry localities have always deeply-toothed leaves while the aquatic forms have less deeply-toothed, sometimes almost entire leaves, in which feature they approach S. undiilata very closely. The cell-walls are however always more highly thickened than in the latter species, especially .at the angles, and the postical lobe of the leaves are longer and narrower obovate (in S. midnlata almost circular). $ plants and fruit are of frequent occurrence. 84. Scapania undulata (L.) Dum. Very common on stones and gravelly soil in rivers, occasionally also on inundated ground in swamps and moss bogs. This plant occurs most frequentty in the low land up to about 300 metres, and forms there, especially creeping over stones in the shallow water along rivers, extensive growths in association with Chilo- scyphns polyanthus var. fragilis and Haplozia cordifolia. Not rarely it is also met with at higher levels, for instance near Dyrafjordur, where it grew abundantly on slopes irrigated by melting snow, 400 — 500 metres above sea-level; and near Holt below Eyjafjall, where it was found abundantly in a stream even at an altitude of about 600 metres. The aquatic forms are usually green; in swamps and moss bogs it often forms extensive, thick carpets, reddish-brown or almost purple in colour. It is frequently found in fruit. The leaves are entire or have a few obtuse teeth at the margin, but forms sometimes occur with more deeply toothed leaves or even with the leaf-margin entirely toothed, in the latter case it may be difficult to distinguish the plant from S. di'ntata and from the large aquatic forms of S. irrigua. The latter, however, have always cells more thick-walled especially at the angles, while S. undulata has always thin- walled leaf-cells. 85. Scapania curia (Mart.) Dum. Common on rocks coated with soil, damp sandy or gravelly Around and on peat, occasionally also on boggy ground up to about 400 metres above sea-level. Near Isafjordur and in Esja it was collected at an THE BRYOPHYTA OF ICELAND 427 altitude of almost 500 metres, g plants are common, fruit rather rare. The majority of the plants bear gemmae. Var. gritif'Hlftta (Mass.) C. M. S. Iceland: Reykir!; Vestmannaey!. NW. Iceland: Armuli!. Var. rosacea (Corda) Carr. is only exceptionally met with typically developed, while forms transitional between the present variety and the type are rather common. The plant is usually green or brownish-green, more rarely reddish. On damp ground it becomes larger and approaches S. irrigua. The leaves vary somewhat in form. The antical lobe is usually pointed, in the lower leaves it is, however, often rounded; it is more rare for all the leaves to be rounded. The leaf-cells are as a rule thin-walled or somewhat thickened at the angles. Forms with highly thickened, red- dish-brown cell-walls are more rare, and occur always in exposed localities. 86. Scapania Bartlingii (Hampe) Nees. Scapania Carestiae de Not. S. Iceland: Drangshlid associated with Amphidium Moiigeottii and Bryum archangelicnm (H.J.)!. Note. Scapania nemorosa is enumerated in the majority of the older lists, but all the specimens in the collections belong to Sca- j)ania nndulata. FAM. RADULOIDE.E. 87. Radula complanata Dum. Gottsche. S. Iceland: Hornafjordur!. E. Iceland: Hof!; Djupivogur!; Seydisfjordur !. X. Iceland: Thrastarholsargil, fr. (O. D.)!. W. Iceland : Flatey (Grl.)!; Budahraun (H.J.)!. Common in SW. and S. Iceland!. The plant is common in E., W. and S. Iceland, while it appears to- be absent from NW. Iceland and to be rare in N. Iceland. It occurs only in the lowlands and rarely ascends higher than about 300 metres. In a few localities in Esja and near Kolvidarhol it was collected at an altitude of about 400 metres. It grows especially on dry, or only slightly damp, shaded rock-sides, mostly in clefts and caves, in company with Mctzgcria farcatu, Lcjciinca cavifolia, etc., and often bears gemmae and in S. Iceland fruit also. It was sometimes col- lected on the bark of trees, viz. on birch on Flatey and on mountain ash in Budarhaun. FAM. MADOTHEGOIDE.E. 88. Madotheca Cordseana (Hubener) Dum. Madotheca rivularis (Dicks.) Xees. "In Islandia" (Morch ;!.' E. Iceland: Hof !: Seydisfjordur (H. J.)!; Beru- ijordur!. NW. Iceland : Dvrafjordur! at an altitude of about 150 metres; 28* 428 A. HESSELBO Dynjandi!; Grunnavik! at an altitude of about 270 metres. W. Iceland: Nordredalur!; Brynjudalur (Grl.)!; Reykjavik (Grl.;!); several places in Esja!. Common in S. Iceland!. Vestmannaey! This plant is most widely distributed in S. Iceland where, as on Vestmannaey, it is common on more or less damp rock-sides especially in clefts of the tuff mountains on Fljotshlid and below Eyjafjall. On Vestmannaey it grew sometimes in abundance among fallen stones in Heljusdalur, and sometimes on slopes associated with Thu.id.iiim abic- tinum and Hylocomium spp. In E. and NW. Iceland it was rarer and generally occurred only sparingly on faces of basalt rocks immediately above the surface of the water of rivers or on damp slopes among stones. This species has not yet been recorded from N. Iceland. FAM. JUBULE^E. 89. Frullania dilatata Nees. W.Iceland: Flatey, on mountain ash (name of finder not stated); Dalasysla, Melar, on sea-fowl cliffs (H.J.)!. Only sterile specimens have been found. 90. Frullania Tamarisci Nees. Common both on dry and on somewhat damp rocks in compan}7 with Hypnacece, Grimmia spp., Antitrichia curtipendula, etc.; in Rhaco- mitriam heaths (both R. cancscens and R. hypnoides); on slopes among Hylocomium spp.; on the top of knolls in marshes, etc. I do not think the plant occurs at a much higher altitude than about 300 metres and it is always sterile. 91. Frullania fragilifolia Tayl. SW. Iceland: Hafnarfjordur, in a lava cave (Grl.)!; Kolvidarhol!; on a rock-face at an altitude of about 400 metres associated with Radula and Lejcaiiea. 92. Lejeunea cavifolia (Ehrh.) Lindb, Lcjeunea serpyllifolia (Dicks.) Spr. "In Islandia" (Morch)!. \V. Iceland: Snsefellsnes!; Sandur in a lava cave (H.J.)!; Hafnarfjordur in lava caves!; Kolvidarhol!. S. Iceland: Seljaland (Stp.)!; common on Fljotshlid and below Eyjafjall!: Thingvalla- hraun!. This plant is common in S. Iceland where it grows especially on shady rock-sides in the clefts and caves of tuff mountains, associated with Metzgeria furcata, Madotheca Cordceana, Amphidium Moiif/eoltii, etc. The habitat of greatest altitude is near Kolvidarhol at about 400 metres above sea-level , there it grew on a rock-face associated with Iladnla and Frullania fragilifolia. THE BRYOPHYTA OF ICELAND 429 Besides in the tuff districts, it is also rather frequent in the lava- lields where it grows at the bottom of deep, damp clefts, but as a rule only in small quantities. Sterile specimens only have been found. FAM. ANTHOCEROTACE.E. 93. Anthoceros punctatus L. W. Iceland: Reykholtdalur (Ho.; Grl.;!). S.Iceland: Reykirdalur!; Sydri Reykjahver!. This species was first collected by Koenig and figured in Flora Danica, tab. 396. It occurs near the majority of the hot springs in Reykirdalur. It grows there abundantly on damp clay-flats with a temperature of 20° -30°, associated with Fossombronia, Haplozia creiialata and Archidium, especially on slopes immediately above the hot water. It almost always bears numerous capsules. 430 A. HESSELBO II. SPHAGNALES. 1. Sphagnum imbricatum (Hornsch.) Russow. S. Austim Sull. S. Iceland: Thorlakshver and Laugarashver near Skalholt!. It grew there on the warm substratum along the outlets from the hot springs in immense yellowish-brown cushions as much as 25 cm. deep. 2. Sphagnum cymbifolium (Ehrh.) Hedw. W. Iceland: near several hot springs in Reykholtdalur!. S. Iceland: Thorlakshver!; sydri Reykjahver!; Laugarvatnshver ! ; Hurdarbak (H. J. !). In all the above localities it grows on damp ground around hot springs. 3. Sphagnum medium Limpr. NW. Iceland: Baeir!; Armuli!. S. Iceland: Common in the district around Skalholt!. W. Iceland: Reykjavik! The plant grows everywhere in wet bogs. 4. Sphagnum papillosum Lindb. \V. Iceland: Reykjavik!, common on boggy ground; Reykholtdalur (Grl.;!), around numerous hot springs. S. Iceland: Hraun; Grimstadr (H. J.)!; Hraundalshraun (H. J.)!; Sydri Reykjahver!. In Reykholtdalur Sphagnum papillosum constitutes the bulk of the vegetation around the hot springs and, for instance at Deildatunguhver, covers large areas of the warm, damp ground with cushions as much as about 20 cm. deep. It appears to be rather widely distributed in S. Iceland and is found there, as near Reykjavik, on the knolls in the bogs, sometimes on a rather dry substratum. 5. Sphagnum inundatum Russow. W. Iceland: Grundarfjordur (H. J.!). S. Iceland: Thorlakshver!; Sydri Reykjahver!. In the two latter localities it grew along the outlets from the hot springs, near S37dri Reykjahver it grew also on the knolls in a small bog near the spring. THE BRYOPHYTA OF ICELAND 431 6. Sphagnum Gravetii Russow. N\V. Iceland : Hesteyri !. It grew there in pools in company with a very large form of Hypnnm revolucns v. Cossoni. 7. Sphagnum compactum De Candolle. S. rigidum Schimp. S. Iceland: Nuphlidarhals near Krisuvik (Stp.)!. 8. Sphagnum teres (Schimp.) Angst. Very common everywhere on damp ground up to a height of about 600 metres above sea-level. S. teres is the most commonly occurring species of this genus and is almost as frequent in the lowlands as in the Alpine region, at high levels. It grows both on knolls in bogs and on more or less damp slopes and is also common on warm ground. It is almost always green or pale yellowish-green in colour. Forms with appressed leaves are by far the most frequent; f. squarrosulum (Lesq.) is met with here and there, e. g. : Esja, Akureyri, Stadr near Hrutafjordur and Laugarashver. The walls of the chlorophyll-cells are very often distinctly papillose. Only sterile specimens have been found. 9. Sphagnum squarrosum Crome. N. Iceland: Mvvatn (Grl.!); Litlu Borgarkatlar (St.) ! ; Grimsey (O. D.)!. N\V. Iceland: Isafjordur!; Grunnavik!; Sugandafjordur!. In NW. Iceland it is rather common up to about 300 metres above sea-level. It grows there sometimes on knolls in bogs and sometimes on more dry ground, thus, near Isafjordur it grew in several places on slopes stretching down towards the rivers. Only sterile specimens have been found. 10. Sphagnum fimbriatum Wils. X. Iceland: Akureyri!; Geitaskard!. NW. Iceland: Dynjandi!; Laugar- land!. \V. Iceland: Ketilstadr (H. J.)!; Stykkisholmur (H. J. ; !) ; Xordredalur in the district of Borgarfjordur!. S. Iceland: Geldingsey (H. J.)!. This plant grows usually on very wet ground in bogs and is no doubt commonly distributed in northern and western Iceland. Thus, near Stykkisholm it was common in bogs, and also around Akureyri where it occurred abundantly up to about 400 metres above sea-level. 11. Sphagnum Girgensohnii Russow. E. Iceland: Eskifjordur (H. J.)!; common near Seydisfjordur!. N. Ice- land: common near Eyjafjordur (O.D.;!); Geldingafell (St.)!; Hafrardalur 432 A. HESSELBO (St.)!. Hvaneyrardalur (St.)!. NW. Iceland: common near Isafjordur!; Dyrafjordur!; Dynjandi!. W. Iceland: Budir (H. J. )!; Nordredalur in Bor- garfjordur!. S. Iceland: Almannagja!; Laugarvatn!; Ingjaldsholl (H. J.)!; Heidi in Myrdalur (H. J.)!; Seljaland!. Commonly distributed both on knolls in bogs and on drier ground. Thus, in lava-clefts near Thingvellir, it is frequently met with on humus- covered blocks associated with Rhacomitriam hypnoides and Hylocomium spp. It is of most frequent occurrence in the lower country, but near Eyjafjordur it ascends to about 600 metres and near Isafjordur to about 400 metres above sea-level. Fruit was found in several places. It occurs especially in orthocladous forms. 12. Sphagnum Russowii Warnst. S. Iceland : Thingvellir!. 13. Sphagnum Warnstorfii Russow. Common on knolls in bogs and on damp ground on slopes up to a height of about 500 metres. Reddish forms are of most frequent occurrence, violet, green and yellowish-green forms are far more rarely met with. Only sterile spe- cimens have been found. 14. Sphagnum rubellum Wils. Common on knolls in bogs and on \vet slopes especially in the lowlands, but it also frequently ascends to about 500 metres above sea- level. Red and violet forms are frequent, green ones are rarer. Only sterile specimens have been found. 15. Sphagnum acutifolium Ehrh. "In Islandia leg. Morch"!. N. Iceland: Hof (O. D.)!. NW. Iceland: Isafjordur!; Armuli!. W.Iceland: Reykholtdalur on warm ground (Grl.;!); Reykjavik!; between Thingvellir and Geysir (Grl.!). Occurs here and there on boggy ground in the lowlands and as a rule rather sparingly. Near Isafjordur it was found in a bog at an altitude of 250 metres. Only sterile specimens have been found. 16. Sphagnum subnitens Russ. et Warnst. NW. Iceland: Bseir!; Thorvaldsdalur (St.)!. W. Iceland: Grund!; Snseldubeinstadahver in Reykholtdalur!; Reykjavik (H. J.;!). S. Iceland: Laugarashver!; Borg (H. J.)!; Krisuvik (Stp.)!. Found here and there in NW., W. and S. Iceland where it occurs both in bogs and along the margin of hot springs. It is frequent around Reykjavik where it was also gathered in fruit. It is as a rule pale yellowish-green in colour. Near Laugarashver a f. violasccns was found growing in large cushions on warm ground. THE BRYOPHYTA OF ICELAND 433 17. Sphagnum Lindbergii Sch. W. Iceland: Ketilstadr among S. fimbriatum (H..I.)!. 18. Sphagnum riparium Angst. X\Y. Iceland: Thoroddstadaengjar (St.)!; common in pools and in very wet parts of bogs near Jokulsfjordur!. 19. Sphagnum angustifolium C. Jens. X.Iceland: Akureyri!. W.Iceland: Reykholtdalur near a number of hot springs!. S. Iceland: Reykirdalur!; Laugarashver !. This species occurs abundantly along outlets from the hot springs in deep cushions of a pale green, yellowish or light brownish-yellow colour. The leaves are distinctly wavy in all the plants from a warm substratum. Its occurrence at Akureyri is peculiar; there it grew at an altitude of about 500—600 metres on wet boggy ground as a slender, pale-green, but otherwise typical, form. Only sterile specimens have been found. 20. Sphagnum Dusenii C. Jens. \V. Iceland: Snseldubeinstadahver in Reykholtdalur!. In the above locality it grew in large yellowish-brown tufts in warm water of a temperature of 25°, near a hot spring. 434 A. HESSELBO MUSCI VERI FAM. ANDRE/EACE^E. 1. Andreaea petrophila Ehrh. Very common all over Iceland. In the lowlands it grows in small round cushions on blocks and on rocks in dry situations and in such localities it is often the dominant species. On mountain heights, where it is frequently met with right at the upper limit of vegetation, it often descends upon the ground, even upon damp gravelly flats, where it forms extensive cushions almost black in colour. Fruit is almost al- ways present. Note. Andrecea rupestris L. — A. Rothii W. M. is recorded by Morch from Iceland and is figured in Flora Danica, tab. 2125, but Morch's specimens must be referred to A. petrophila. FAM. ARCHIDIACE.E. 2. Archidium phascoides Bridel. W. Iceland: Reykholtdalur!, near all the hot springs (Grl.;!); Englands- hver!. S. Iceland: Reykirdalur!; Reykjanes (Ostf.)!; Kolvidarhol ! ; Thorlaks- hver!; Laugarashver !; Sydri Reykjahver!; Geysir!. Archidium phascoides occurs in the collections under different names. It was first collected by Gronlund and determined by Zetterstedt as Leskea nervosa. Afterwards this specimen with several others were re -determined by Gronlund as Catoscopium nigritam var. Gronhmdii established by C. Jensen. All the plants collected by Ostenfeld from Reykjanes are determined by C. Jensen as Pohlia nutans v. filicaulis. The reason for all these erroneous determinations will be found in the fact that the plant is almost always found barren and in leaf- form and cell-tissue presents a certain resemblance to mosses belonging to quite different groups, which often leads to the belief that the spe- cimens in question are stunted forms or have been affected by the warm substratum: thus, certain forms bear a striking likeness to a slender Amblystegium compactum. The plant is typical of warm clay flats, and in S. and W. Iceland it is met with around every hot spring. On the warm clay flats with a temperature of 20°— 40°, it forms extensive yellowish-green mats 1—2 cm. high. On slopes stretching down towards the boiling water and along outlets from the springs it is also frequently found growing within a few centimetres from the water, usually mixed THE BRYOPHYTA OK ICELAND 435 with Haplozia crennlata and Fossombronia Dumortieri, more rarely with Gymnocolea inflata. It is almost always sterile; on plants from Thor- lakshver flowers as well as a few ripe capsules were found, besides, here and there at the bottom of the tufts, the characteristic large spores (9. 6. 1912). Note. Phascum cuspidatum, Ephemernm serratum and Sphcerangium muticum are enumerated on older lists, but no specimens of these species are to be found in the collections and their occurrence in Ice- land is very improbable. FAM. WEISIACE^E. 3. Gymnostomum rupestre Schleich. E. Iceland: Geithellir!. N. Iceland: Akureyri!; Modruvellir: Hof (0. D.)!. W. Iceland: Brynjudalur (Grl.) !; Esja!. S. Iceland : Skalholt !; Thingvellir!. Around E}rjafj6rdur it is common on damp rocks up to a height of about 300 metres; it was also found in numerous localities in SW. and S.Iceland and is common, for instance in Esja. It occurs especi- ally on damp rock-sides near waterfalls and in clefts, often forming extensive mats; now and then it is also found in dry localities. Only sterile specimens have been found. 4. Hymenostylium curvirostre (Ehrh.) Lindb. Barbula curvirostris Lindb. N. Iceland: Mwatn (Grl.)!. W. Iceland: Reykholt (Grl.)!, in both localities sparingly and also sterile. S. Iceland: Merkjafoss (F.)!; Bar- karstadr, fr.!; Holt, fr.!; Vestmannacy, fr. !. In S. Iceland the plant is no doubt common on faces of damp tuft- rocks. In several localities near Barkarstadr and Holt it occurred abundantly in clefts along rivers or in caves and in depressions in tuft rocks; it was usually richly in fruit, and associated with Preissia coin- mutata, Fegatella, Haplozia riparia, etc. On '"Kleven" on the island of Vestmannaey it grew on the face of a tuff rock, through which water was percolating, forming with Haplozia riparia large cushions which were saturated with water. 5. Anoectangium compactum Schwgr. Pleurozyyodon cestiuus (Hedw.) Lindb. "In Islandia" leg. Morch! and figured in Flora Danica, tab. 1893, fig. 2, under the name of Gymnostomum curvirostre. E. Iceland: Seydisfjordur, common!; Berufjordur, common!. W. Ice- land : Grundarfjordur (H. J.)!; Hafnarfjordur (Grl.;!); Esja!; Svinahraun!. S. Iceland: very common!; Vestmannaey!. This plant is very common in S., SW. and E. Iceland, but it does, not appear to occur in N. and N\V. Iceland. It grows especially on damp 436 A. HESSELBO rocks, e. g. on rock-sides along waterfalls and in clefts, where it forms large cushions, often almost one square metre in size, of a peculiar verdigris colour. In the lava-fields of SW. Iceland it is one of the most frequent species on the walls of caves and the sides of clefts. It hardly ascends higher than about 300 metres above sea-level. It is almost always sterile. The only fruiting specimen was collected by Morch. but no habitat is given. 6. Weisia crispata (Br. germ.) Jur. SW. Iceland: Reykjavik, fr.!. SE. Iceland: Hornafjordur!; SW. Ice- land: Alafoss!. Near Reykjavik it grew in crevices of basalt rocks associated with Encalypta rhabdocarpa and Bryum elegans var. carinthiacam. The fruit had just ripened on June 6, 1909. Near Hornafjordur also it grew in small crevices of basalt. Only sterile specimens have been found. 7. Weisia viridula (L.) Hedw. S. Iceland: Vik, associated with Brachythecium velntimim (H. J.)!. Vest- mannaey, Helgafell!, on a humus-covered block of lava. Only sterile specimens have been found. The species is recorded by Morch from Iceland, but no specimens of it are to be found in the collections. 8. Weisia Wimmeriana (Sendtn.) Br. eur. N. Iceland: Hof near Eyjafjordur (O. D.)!, fr. It grew there mixed with Eurynchium diversifoliiim on rocks coated with soil. 9. Dicranoweisia crispula Hedw.) Lindb. Very common all over Iceland. Dicranoweisia crispula is one of those species which is of equal frequency in all parts of Iceland, both at the coasts and in the high- lands, and at all altitudes up to the snow-line. In the low land it grows, like Andrecea, on dry stones and rocks, but like the latter, it descends to the ground on mountain heights where it forms, both on the ground or on blocks of rock, dense, jet-black cushions. It is almost always found in fruit. Note. Dicranoweisia cirrata is recorded by Hornemann, but has undoubtedly been confused with D. crispula. 10. Dicranoweisia compacta (Schleich.) Schimp. N. Iceland: Hof near Eyjafjordur (O. D.)!. Only sterile specimens have been found. THE BRYOPHYTA OF ICELAND 437 FAM. RHABDOWEISIACE.E. 11. Cynodontium polycarpum (Ehr.) Schimp. Seydisfjprdur '^C. Hansen) !. This species together with the var. strumiferum , is recorded by Vahl, but has without doubt been confused with another species, pro- bably a Dicrannm or Oncophorus. Morch also records both forms from Iceland, but of his specimens in the Botanical Museum in Copen- hagen some are Dicrannm Starckei, and some are Ceratodon purpurcus. Cynodontium gracilescens var. tenellnm is recorded by Carrington from Akureyri, but has undoubtedly been confused with another species. 12. Dichodontium pellucidum (L.) Schimp. Very common ever37w7here on damp ground. This plant is most widely distributed in the lowlands and is found there everywhere on damp ground, both in bogs and on gravelly soil along streams, and also on soil-covered rocks. In the lowlands it usually grows mixed with all kinds of other mosses in their tufts and is, as a rule, low in growth and short-leaved. On rocks near the water, where it is also frequent, more vigorous forms occur in unmixed tufts, 2 — 4 cm. high. At higher levels it occurs more sparingly, but is nevertheless fre- quently found up to about 600 metres above sea-level. Only sterile specimens have been found. FAM. AONGSTRCEMIACE.E. 13. Aongstroemia longipes (Sommerf.) Br. eur. E. Iceland: Bornafjordur!; Hof!; Seydisfjordur !; Vallanes!. N. Ice- land: Akureyri (O. D.;!); Husavik!; Vidimyri!; the Tvera!; Dettifoss!; Stadr near Hrutafjordur!. NW. Iceland: Armuli!. W. Iceland: Haukadal!; Lundur!; Alafoss!. S.Iceland: Breidabolstadr!; Barkarstadr!; Seljaland!. This species is doubtless common everywhere, but is often over- looked on account of its minute size. It grows on damp ground, most frequently as single specimens scattered among other mosses; more rareh7, as for instance near Hornafjordur and Breidabolstadr, abundantly on peat along ditches. Near Lundur it grew abundantly associated with Dicranella Schreberi, Bryum lacustre, Dichodontium and other species in places where the peat had been pared off. In the majority of the cases the specimens were not found until the material brought home had been investigated, because in habit the}7 exactly resemble the tiny Pohlia-forms of wide occurrence, or a small, sterile Anomobryum. On boggy ground it was usually collected together with Dichodon- tiam pellucidum, Oncophorus Wahlenbergii, Mecsia trichoidcs, Bryum spp., etc. On gravelly soil near Stadr it was found associated with Dicranella crispa, Didymodon rubellus, Blasia pusilla and Haploiia atroinrens and in several places with Distichium inclinatum. It occurs both in the low 438 A. HESSELBO lands and up to 500—600 metres above sea -level. Near Akureyri it was found on a damp flat at about 500 metres. Near Barkarstadr it occurred abundantly on boggy ground at about 530 metres, and near Seljaland it was also frequent at an altitude of about 500 metres on a moss-grown gravelly flat. Only sterile specimens have been found. FAM. DICRANACE.E. 14. Oncophorus virens (S\v.) Brid. Very common on damp ground. It grows both on wet humus- covered rocks and in bogs, and also on damp gravelly ground, some- times as unmixed tufts and sometimes mixed with other mosses; it is of equal frequency at all altitudes as far upwards as 600—700 metres. It often occurs in great quantities and usually fruits richly. In the lower districts the fruit ripens about July 1st. In S. Iceland this species is either wanting or rare in the lowlands up to a height of about 300 metres (it has not been found on Vestmannaey), but from this height up to the snow-line it occurs abundantly in bogs. Var. .serrfttfts Br. eur. occurs occasionally on wet rocks. • 15. Oncophorus Wahlenbergii Brid. One of the most commonly occurring mosses; it is found every- where in damp localities just like 0. virens. It is very common espe- cially in bogs, except in S. Iceland where, like O. virens, it has its dis- tribution from an altitude of 300 metres upwards. Var. ft comp€ictus (Punch) Br. eur. E. Iceland: Skreiddal!; Seydisfjordur!. It grew .in both localities on knolls in bogs. Var. elottfjatum Hagen. W.Iceland: Nordredalur!. It grew there on boggy ground in association with Sphagnum teres, S. rubellum and S. fim- briatum in loose tufts about 6 cm. high. Although typically developed forms of Oncophorus Wahlenbergii and O. virens differ so widely from each other that they are not likely to be confused, yet so many transitional forms occur, especially in Alpine habitats, that very often it is a matter of opinion to which species such a form should be referred. On the same plant leaves may be found which, as regards the cells of the leaf-base, resemble sometimes O. Wahlenbergii and sometimes 0. virens; also the leaf-margin is more or less recurved or plane. 16. Dicranella squarrosa (Starkc) Schimp. E.Iceland: Seydisfjordur!; Skorastadr (H. J.)!. N.Iceland: Husavik!; near Eyjafjordur (O. D.;!), fr. ; Laekjarmot!. NW. Iceland: Very common!. W.Iceland: Vogur (H.J.)!; Esja!; Reykholtdalur!. S. Iceland: Holt!. This plant grows almost always in water, especially on inundated gravelly ground by streams, on stones and in moss bogs, more rarety on wet marshy ground. In NW. Iceland it is one of the mosses of most frequent occurrence being found in abundance associated with THE BKYOPHYTA OF ICELAND 439 Philonotis seriata, Oncophorus Wahlenbergii, Scapania nliginosa, Haplozia co rdi folia and Chiloscyphus polyanthus var. frag His on inundated gravelly ground up to about 300—400 metres above sea-level. In N. Iceland it is also rather common. Near Seydisfjordur it was found only at a height of about 300 to 500 metres above sea-level, but was common there in small streams associated with Scajmnia undiilata, Hijpnnm ex- anmilatam, Haplozia cordifolia, etc. In Reykholtdalur this species was found in several places near hot springs, even on stones in warm water with a temperature of 30°. In S\V. and S. Iceland it occurs rarely and more sparingly; near Holt it grew in several places at an altitude of loO— 600 metres. The plant is almost always found sterile. One specimen collected by O. D. near Hof in Eyjafjordur 12. 6. 1897) bore a few capsules which had thrown off their lids. The J1 plant was found only near Bceir in XW. Iceland growing in low tufts, about 1 cm. high. 17. Dicranella Schreberi (Sw.) Schimp. Anisothecium crisp um Schreb.) Lindb. X.Iceland: Hof near Eyjafjordur (O. D.)!; Akureyri $!. W.Iceland: Lund u r!. Xear Akureyri it grew in damp, peaty ground immediately north of the town and near Lundur, associated with Bnjnm lacnstre, Aong- strcemia longipes and Dichodontium pellncidiim, on a wet flat from which the peat had been pared off. 18. Dicranella crispa (Ehrh.) Schimp. Very common on damp ground, both on peat and on sandy or gravelly soil by streams. It occurs only in the lowlands, and has hardly been found higher than at an altitude of about 200 metres. Fruit is always present in abundance and ripens about August 1st. At this time also the setse of the capsules of the ensuing year have reached their full length. Xote. Dicranella heteromalla is recorded by Zoega and Horne- mann from Iceland, but was. undoubtedly confused with another species. 19. Dicranella subulata (Hedw.) Schimp. Dicranella secunda Sw.) Lindb. Iceland (Morch)!, some of the specimens are correctly determined, some must be referred to Ditrichnm homomallnm. Krisuvik (Stp.)!. N. Iceland: Husavik!. XW. Iceland: Kaldalon!; Gnupsdalur near Dyrafjordur!. Moreover, Gronlund records it from Hvammur and Thingvellir, but both specimens are wrongly determined, being Dicranella crispa and Dicramim Blyttii. This species was collected in small quantities only, but everywhere in fruit. Xear Husavik it grew on peat, and on July 11, 1909 it bore 440 A. HESSELBO both quite young capsules and also old lidless capsules. In Gnupsdalur it grew along the banks of streams with Scapania subalpina and Cepha- lozia bicuspidata. 20. Dicranella cerviculata (Hedw.) Schimp. Iceland: (Morch)!. NW. Iceland: Stadr on Snaefjallastrond ^Stp.)!; Dynjandi!. W.Iceland: Borgarnes!; Kollafjordur!; Reykjavik (Grl.;!). S. Iceland: Thjorsa (Stp.)!. The plant was found everywhere in fruit. Near Borgarnes and Reykjavik the fruit was almost ripe at the beginning of August. It grows on peat, especially on the rather dry margins of turf pits and ditches and occurred abundantly especially in several places near Reykjavik. 21. Dicranum fulvellum (Dicks.) Sm. Collected in Iceland by Morch (no doubt near Middalurj and figured in Flora Danica, tab. 2002, under the name of D. Morchianum Hornsch. S. Iceland: Holt!; Seljaland!; Thingvallahraun!. SW. Iceland : Svinahraun !. This species is recorded by Gronlund from Svinaskard and Thing- valla, but the specimens from both localities are wrongly determined, being really D. falcatum and D. Blyttii respectively. Dicranum fulvellum has been only found in the south-western part of Iceland, where it appears to be frequent. In Svinahraun, where the altitude hardly exceeds 300 metres, it was found rather sparingly (June 3rd) on the top of lava-blocks, in fruit which was almost ripe. On Eyjafjall it occurred in several localities above Holt and Seljaland at an altitude of 300—700 metres. It grew either on blocks of basalt or more rarely on gravelly ground in company with Gymnomitrium concin- nalum. At the end of July the fruit was ripe everywhere, and generally the capsules had thrown off their lids. 22. Dicranum Andersonii (Wich.) Schimp. SE. Iceland: Hof!; coastal cliffs near Alftafjordur!. S. Iceland: Holt!; Vestmannaey !; Thingvellir!. Near Hof it occurred rather commonly on low basalt ridges, where it usually grew in crevices in small cushions about 3 cm. high. Here the fruit had just ripened on June 15th and the lids still persisted. Near Holt it was found rather frequently on tuff rocks up to a height of about 300 metres. Thus, it grew abundantly, for instance on the vertical northern face of a tuff rock sometimes in small tufts, sometimes mixed with Grimmia apocarpa, Pogonatum nrnigernm, Pohlia grandi flora. Anthelia nivalis and Gymnomitrium concinnatnm. On Vestmannaey the plant grew abundantly on blocks of lava lying on the slope of Helga- fell. It occurred there everywhere in small scattered tufts associated with Grimmia apocarpa, Rhacomitrium siidelicnm. R. fasciculare and An- drecea petrophila. The fruit was ripe on July 5th; a few had thrown off their lids. THE BRYOPHYTA OF ICELAND 441 In Iceland Dicranum Andersonii is i\ decidedly lowland plant, which is probably widely distributed in the southern and south-eastern parts of the country. It occurs especially near the coast; in the interior of the country it has been found only near Thingvellir, where it grew very sparingly on a lava block in company with D. fulvellnm, which it resembles in the fact that the peristome teeth are wide-spreading when dry. Dicranum Andersonii is however easily distinguished by its shorter seta and by the extremely thick-walled cells of the capsule-walls and by the absence of stomata. 23. Dicranum falcatum Hedw. E. Iceland: Lonsheidi!, at an altitude of about 400 metres; Beru- fjordur!. N.Iceland: Ljosavatnsberg!. NW. Iceland: Dyrafjordur!; Isa- fjordur!. W. Iceland: Snaefellsnes: Saxarhol (H.J.)!; Frodarheidi (H.J.)!; Reynivellir (Grl.) ! ; Svinaskard (Grl.) ! ; Kolvidarhol ! ; Esja !. S. Iceland : Holt ! ; Seljaland!. The plant is recorded by Morch from Iceland and figured in Flora Danica, tab. 2003, but Morch's specimens in the Botanical Museum in Copenhagen belong to Dicranoweisia crispala. Dicranum falcalum is a plant characteristic of the damp gravelly flats of mountain heights, where it often occurs abundantly in large, compact, rounded cushions in the neighbourhood of patches of snow. Usually it is not met with until an altitude of about 600 metres; near Kolvidarhol, however, it was common even at an altitude of about 400 metres. This species is very common in NW. and in S. Iceland and occurred also abundantly on Ljosavatnsberg. It is probably common everywhere on mountain heights, but, as for instance in E. Iceland, it has only been collected scantily, as its habitats are snow-covered in June when that part was explored. The fruit, which is always present abundantly, ripens about the middle of July. 24. Dicranum Blyttii Schimp. Dicranum Schisti (Gunn.) Lindb. E. Iceland: Hamarfjordur!. N. Iceland: Reykjaheide!; Vidvik (P. S.)!; Hof (O. D.)!. NW. Iceland: Patreksfjordur (Wiinstedt)!; Glama (St.)!, com- mon on mountain heights!. W. Iceland: 0xarrhyggur!; Svinahraun!; Hafnarfjordur!. S. Iceland: Seljaland!, from an altitude of 350 metres upwards; Holt!, common on mountain heights; Thingvallahraun !. This species is common, at any rate in NW. and SW. Iceland, while it has been found but scantily in E. Iceland and only in a few localities in N. Iceland. But the same is probably the case here as mentioned for Dicranum falcatum, that its habitats, at the time when E. Iceland was explored (June 1909), were covered with snow. Dicranum Blyttii belongs to the Alpine region and is not met with until an altitude of 300 — 400 metres. Near Hamartjordur, however, it grew in the lowlands on rocks near the coast. It grows partly on stones and partly on gravel, and is especially frequent at a height of 600—800 metres, both on gravelly flats soaked by the melting snow, The Botany of Iceland. Vol. I, part II. 29 442 A. HESSELBO and on scattered blocks of rock. It often forms there extensive, blackish- green or almost black cushions, 2 — 3 cm. deep. In lava-fields it occurs associated with several other Alpine species at the bottom of ravines, as on Reykjaheide (at an altitude of about 300 metres), in Thingvallahraun, where it was rather common on fallen blocks in ravines (Gja), and near Hafnarfjordur, where it was also rather frequent in lava-clefts. In Svinahraun it grew abundantly on damp ground in a large depression at the edge of the lava-field. The leaves usually spread erectly, more rarely, for instance in plants from Thingvellir, they are secund. The fruit ripens almost at the same time on mountain heights and in the lava-fields, viz. at the end of July. Near Thingvellir it was found on July 29th with fully ripe capsules, some of which had thrown off their lids. 25. Dicranum Starckei Web. et Mohr. "In Islandia" (determined by Morch as Dicranum polycarpoii). Widery distributed all over Iceland. This species is most widely distributed on damp gravelly flats from an altitude of about 400 metres upwards to the snow-line and is often there, especially from about 400—600 metres, the most abundant constituent of the vegetation, growing in extensive, continuous mats, 2—3 cm. deep. It occurs however also on stones and damp rocks. It is found more scantily in the more low-lying parts of the country, although, especially in NW. and N. Iceland, it is frequent, mixed with other mosses, on gravelly ground by streams. In the southern part of the country it does not appear to descend to a lower level than 300—400 metres. Like Dicranum Blyttii this species grows also in lava-clefts, and it was common on fallen blocks both near Hafnarfjordur and Thingvellir. The plants from these localities were often 5—6 cm. high, with longer leaves, in which feature they approached very closely to D. molle. The direction of the leaves varies considerably, orthophyllous forms are the most frequent, especially on the ground; highly drepanophyllous forms occur more particularly in drier localities, for instance on rocks. Fruit is almost always present. The majority of the specimens collected (June— July) had old, empty capsules, and also young green ones or half-ripe ones which probably ripen late in the summer. 26. Dicranum molle Wils. D. arcticum Schimp. D. glaciate Berggr. E. Iceland: Seydisfjordur!, at an altitude of about 200 metres. N. Iceland: Akureyri!. NW. Iceland: Dyrafjordur!; Sugandafjordur ! ; Isa- fjordur!; Kaldalon!; Dynjandi!. W. Iceland: Snrcfellsnes, Mafahlid (H. J.)!, at an altitude of about 300 metres; Budahraun (H.J.)!; Dalasysla, Vig- holsstadir (H. J.)!, 550 metres alt.; Olafsvig (Morch)!; Svinaskard (F.)!; Esja, Modruvellir!. at an altitude of about 450 metres; Hafnarfjordur!. S. Iceland : Thingvallahraun !. This species is also recorded from several localities by Gronlund, THE URYOPHYTA OF ICELAND 443 but the specimens in the Botanical Museum are wrongly determined; most af them must be referred to D. Starckei or D. angiistiim. Dicmmim mollc usually grows on damp gravelly ground on moun- tain heights. In NW. Iceland it is one of the most commonly occurring mosses on rocky flats, and is common down to about 200 metres above sea-level; but also frequently descends as far down as the bottom of the valley. It grows both on gravelly flats soaked by melting snow and on damp slopes; also on lower levels on heathy soil, with other Dicramim spp. (D. scopurium and D. fuscescens), among Vitcciniiim, Em- pi' t mm, etc., in large tufts which are usually closely interwoven with Lophozia lycopodioides , L. Knnzeana, L. quinquedentata, L. Floerckei, L. uentricosa and other Hepaticas. Near Modruvellir it grew partly on damp gravelly ground, partly intermixed in abundance in Rhacomitrium hyp- /loiY/fs-heaths; in this latter locality also it was mixed with Lophozia spp. In lava-fields it usually grows in company with D. Starckei, commonly, as for instance in the clefts near Thingvellir, in cushions as much as 10 cm. deep. The plants from the latter locality and from Hafnar- fjordurhraun are sometimes not quite typical and approach so closely to D. Starckei, that they can hardly be distinguished. The leaves are sometimes orthophyllous, sometimes drepanophyllous. The fruit, which is always present abundantly, ripens during July. In the district of Isafjordur, however, ripe fruit was frequently found as early as in the latter days of June. 27. Dicranum Bonjeani de Not. D. palustre Br. eur. SE. Iceland: Hornafjordur!; Lon !. N. Iceland: near Eyjafjordur (O. D.)!. W. Iceland: Dalasysla; Ketilstadr (H. J.)!; Reykholtdafur (Grl. !); Reykjavik!. The plants from all the above-mentioned localities agree exactly with D. Bonjeani, but being quite sterile they cannot be determined with perfect certainty. Bog-forms of Dicramim scopariiim have often erect leaves, slightly undulate at the apex, and are then extreme!}' difficult to distinguish from D. Bonjeani. This species grows in bogs, usually on knolls, and is common around Reykjavik and near Hornafjordur. Note. In several older lists Dicramim undnlatnm is enumerated as found in Iceland by Morch and is also recorded by Gronlund from Reykholt and Reykjavik, but all the specimens in the herbaria must either be referred to D. scop a mm or D. palustre. 28. Dicranum angustum Lindb. E. Iceland: Hornafjordur!; Berufjordur!; Lon!; Hof!. N.Iceland: Myvatn (Grl.; determined as D. arcticu /??)!; Stadr near Hrutafjordur!. NW. Iceland: Dynjandi!. W. Iceland: Stykkisholmur!; Reykjavik!. S. Iceland: Asolfskalaheidi near Holt!, at an altitude of about 400 metres. This species is no doubt widely distributed over the whole of Ice- land; it is, at any rate, rather common in E. and SW. Iceland, where 29* 444 A. HESSELBO it often occurs abundantly. It grows on wet boggy ground in loose tufts as much as 6 cm. high, either pure or mixed with Sphagna and Hypniim stramincum and interwoven with Hepaticse such as Lophozia quinquedentata, Scapania irrigua, Cephalozia pleniceps, etc. Only sterile specimens have been found. This species is most widely distributed in the lowlands and has only once been collected at an altitude of 400 metres on Asolfskalaheidi, where it grew plentifully in a bog. Hag en (Musci Norv. Borealis, p. 22) states that D. angustum differs from all nearly allied species, and especially from D. scoparium, in having thin-walled cortical cells; but this distinction does not suffice as regards bog-forms of D. scoparium as in the latter species all transitional stages are found from the thin-walled, hyaline cortical cells of plants from wet ground to the thick-walled, brown cells of xerophilous forms. 29. Dicranum majus Smith. NW. Iceland: Dyrafjordur!; Sugandafjordur!; Isafjordur!. W. Iceland: Neshraun (H. J.)!; Budahraun (H. J.)!. In the two habitats in W. Iceland, both of them on Snsefellsnes, the plants were collected in depressions in the lava-field. In NW. Ice- land, where it is commonly distributed, it grows on the ground on slopes covered with birch coppice, Vaccinium, etc., as far upwards as about 300 metres above sea-level. The majority of the plants collected have slightly secund leaves and entirely resemble D. scoparium in habit. A vigorous form with strongly falcate leaves was found in a birch coppice near Dyrafjordur at an altitude of about 150 metres. Only sterile specimens have been found. 30. Dicranum scoparium (L.) Hechv. Very common. D. scoparium is most widely distributed in the more low-lying parts of the country up to a height of about 400—500 metres, but also ascends frequently to about 700 metres above sea-level. In S. Iceland it appears to be more rare and, as for instance on Fljotshlid and south of Eyja- fjall, was only found in a few localities and very scantily. It grows both on rather dry and on damp ground, and also on rocks and on knolls in bogs, and varies considerably. Orthophyllous forms are the most common, especially on damp ground, while more or less distinctly drepanophyllous forms grow by preference in dry localities, for instance in lava-fields and on rocks. In bog-forms the leaves are slightly undulate at the apex, in which feature it approaches D. Bonjeani. The leaf-apex, especially in orthophyllous forms, is usually short and broad, and faintly toothed, or even quite entire, at the margin, at the same time the lamellse on the back of the leaves develop more slightly or dis- appear almost entirely. Such forms agree well with var. in leg ri folium Lindb. Fruit is found rather rarely; in Nordredalur it was fully developed on August 2nd, but was still green. THE BRYOPHYTA OF ICELAND 445 31. Dicranum fuscescens Turn. Iceland (Wiinstedt, determined by Berggren as D. Scoltiamun}. NW. Iceland: very common!. W.Iceland: Nordredalur!. In NW. Iceland D. fuscescens is the most frequently occurring species of this genus and is very common from the bottom of the valley up to a height of 400—500 metres. It is most widely distributed from about 100 to 300 metres on somewhat damp slopes covered with Vac- cinium-Empetrum heath, where it often constitutes the bulk of the Bryophyte vegetation in association with D. molle, D. scoparium and occasional!}7, D. majns. It is also common on the top of knolls in bogs. The densely matted tufts, which are as much as 10 cm. high, are al- most always interwoven with Hepaticse, especial)}' Lophozia spp., Ce- phalozia pleniceps, C. bicuspidata and Ptilidium ciliare. In Nordredal it was growing in birch coppices in company with Hijlocomium spp. The fruit, which occurs rather frequently, was quite green even in the beginning of July. All the Iceland specimens differ from the typical form and, more or less, especially approach Dicranum congestion without, however, form- ing any real transitional form to the latter. As a rule the leaf-nerve occupies about V* the width of the leaf-base, but occasionally 1/5—1/e only. The cells of the leaf-apex are usually quadrate or roundish, mixed with numerous ones that are irregular in form; rarely, in the main, shortly rectangular, in which feature it approaches var. (ingusti- folium Arn. et Jensen; most frequently arranged more or less distinctly in rows; papillose at back, more rarely almost smooth, but in the same tuft or even on the same stem rather considerable variations occur as regards the development of the cell-tissue and the papillse of the leaves. 32. Dicranum congestum Brid. Very common in E. and N. Iceland and probably also in \V. Iceland, somewhat rarer in S. Iceland. It appears to be quite absent from NW. Iceland and to be replaced there by D. fuscescens. It grows both on a dry and on a somewhat damp substratum, on earth and humus-covered stony slopes and on the top of knolls in bogs, and extends as far upwards as to the snow-line, for instance near Akureyri up to about 900 metres above sea-level. In S. Iceland it has not been found in the low land, but plentifully in several places on the rocky flat, for instance near Barkastadr, 500 metres above sea-level. Var. subspadicenm Arn. et Jensen occasionally occurs in localities similar to those of the type, but transitional forms are of more frequent occurrence. Var. flexicaule (Brid.) Br. eur. N. Iceland: Ljosavatn!, \nBetiila-nana heath; Hof (0. D.)!. Only sterile specimens have been found. Dicranum congestum is so variable a species that it is hardly pos- sible to find two plants which are exactly alike. The nerve occupies 1/e— Vio the width of the leaf at its base, usually 1/s— 1/9. The leaf-cells 446 A. HESSELBO are irregular in form more or less far down the leaf, sometimes far below the middle, sometimes only at the leaf-apex itself; slightly or hardly porose, occasionally strongly porose in the lower half of the leaf, more rarely to near the apex, in the last case the walls are strongly incrassate. Dicranum brcvifolium Lindb. is recorded from Vatnsdalsfjall (Grl., Tillseg til Islands Kryptogamflora, Bot. Tids., 20), but the plant from the latter locality is only a form of D. congestum in which the irregularly shaped cells are strongly incrassate and extend down below the middle of the leaf. Such forms, which, as a rule, are also distinguished by very strong nerves, have been found in several localities, for instance near Berufjordur and about Eyjafjordur. The true D. breuifoliiim, which is dis- tinguished by its shorter leaves, crisped when dry, and its thin-walled cells, which are in a great measure quadrate and in rows, has not been found in Iceland. 33. Dicranum spadiceum Zett. W. Iceland: Hvitidalur (H. J.)!. E. Iceland: Hornafjordur!; Seydis- fjordur!. N. Iceland: Hof (O. D.)!; Vatnsdalsfjall (St.)!. Grows on a damp substratum, especially on knolls in bogs. Only sterile specimens have been found. 34. Dicranum elongatum Schleich. "In Islandia" Morch ! (fr.). N. Iceland: By Hrutafjordur!. NW. Iceland: Dynjandi!; Hesteyri!. W. Iceland: Stykkisholmur !. This species is also recorded from some localities by Gronlund, but the specimens in the collections are wrongly determined, being D. Starckei, and others. D. elongatum grows everywhere on wet, boggy ground. By Hruta- fjordur it w7as common on knolls in bogs along the eastern side of the fjord from Stadrbakki to Stadr, and it was also frequent in bogs near Stykkisholmur. All the specimens collected were quite typical. The nerve was about */4 the width of the leaf at its base. With the exception of the specimen found by Morch only sterile specimens have been collected. Note. According to Gliemann, Dicranum montanum was found in Iceland by Morch, but no specimens of it are to be found in the collections, and the record of this species is undoubtedly due to an er- roneous determination. 35. Campylopus Schimperi Milde. N. Iceland: Geitaskard!. E. Iceland: Hornafjordur!; Lon!; Beru- fjordur!. W. Iceland: Reykjavik!; Esja (Grl.)!. S. Iceland: Breidabolstadr!. Commonly distributed in South-western and South-eastern Iceland on damp ground in bogs, where it forms compact cushions, 2—3 cm. deep. It has only been found in the low land. THE BRYOPHYTA OF ICELAND. 447 36. Campylopus flexuosus (L.) Brid. N. Iceland: Myvatn (Grl.M; Reykir near Svinavatn (Grl.)!. \V. Iceland: Near hot springs in Reykholtdalur: Deildatunguhver (Grl.;!); Skribla (Grl.)!; Hagindishver!, etc. This species has been found only on steaming clayey flats near hot springs in North and West Iceland. In Reykholtdalur it is frequent on a warm substratum, and was found, for instance near Deildatungu- hver, in large mats, about 2 cm. deep, on warm clayey flats with a tem- perature of about 40° just below the surface. 37. Campylopus fragilis (Dicks.) Br. eur. S. Iceland: Laugarashver near Skalholt. It grew there on warm clayey flats close to the outlet from the spring. 38. Trematodon ambiguus (Hedw.) Hornsch. W. Iceland: near Borgarnes!. It grew there rather scantily on damp peaty soil by the road, in company with Brynm inclination , Pogonatum nanum , Scapania curta, etc. The fruit had just ripened on Aug. 2nd, but the lids had not been thrown off. Note. Leiicobryum glanciim is 'recorded by \7ahl and Home- man n as found in Iceland, but neither the name of the finder nor the habitat is given. No specimens of this species are to be found in the collections. FAM. FISSIDENTACE^E. 39. Fissidens bryoides (L.) Hedw. N. Iceland: Hof near Eyjafjordur (O. D.)!. S. Iceland: Krokur (H. J.)! Almannagja!. In Almannagja it grew very scantily among other mosses on soil- covered stones at the bottom of a lava-cleft. Near Hof it grew on damp ground by a waterfall. The fruit, on the specimens from both localities, was ripe when collected (June 12). 40. Fissidens osmundoides (Sw.) Hedw. Common on damp ground in bogs, at the base of rocks, in rock- clefts, etc., sometimes in low, dense tufts, sometimes mixed with other mosses. The plants are almost always found sterile. Only in Reyk- holtdalur, where it grows very abundantly on warm, boggy ground, has it been collected in fruit. It is most widely distributed in the lowlands up to about 300 metres above sea-level, but it may occur, although scantily, as high as about 500—600 metres. 448 A. HESSELBO 41. Fissidens adianthoides (L.) Hedw. N. Iceland: Hof near Eyjafjordur , fr. (O. D.)!. W. Iceland: Klepp- jarnsreykir (Grl.!); Laugarnir near Reykjavik (Grl.)!; bog near Reykjavik, fr. !; Kollafjordur! Rare and scanty on boggy or warm ground. Note. Fissidens taxifolius is recorded by Z o e g a and H o r n e m a n n from Iceland (without finder, habitat or specimens in the collections) and by Gronlund from Myvatn; but Gronlund's specimen belongs to F. osmundoides. 42. Fissidens decipiens De Not. W. Iceland : Sandur (H. J.)!; Hafnarfjordur!. This plant grew in both localities in lava-clefts, associated with Lejennea serpy Hi folia. FAM. SELIGERIACE.E. 43. Blindia acuta (Huds.) Br. eur. Very common on wet rocks in or by rivers and waterfalls up to about 400—500 metres above sea-level, occasionally also on the ground and often in great abundance. The fruit, which is almost always pre- sent, ripens in the beginning of July. At a greater altitude it occurs more scantily, but may nevertheless be met with as far upwards as 600—700 metres. FAM. DITRICHACE.E. 44. Ceratodon purpureus (L.) Brid. Common on rocks, lava-flats, sandy soil, peat, etc. especially in N. and NW. Iceland, and on lava-flats in the interior of the country. It is less frequent in E. and S. Iceland. The fruit, which is usually present, ripens in the first half of July. It varies considerably, especially in leaf-form. Forms with shortly pointed or almost obtuse leaves (var. brevifolius) are the most frequent. 45. Ditrichum tortile (Schrad.) Lindb. E. Iceland: Seydisfjordur!, sterile. It was growing there on damp gravelly soil along a river, inter- spersed in a Hepaticse-mat formed by Alicularia scalaris, A. geoscypha, Anthelia Juralzkana, Lophozia ventricosa, etc. 46. Ditrichum nivale (G. M.) Limpr. E Iceland: Rerufjardarskard!, at an altitude of about 500 metres, fr. The plant was growing very scantily in a cushion of Anthelia Juratzkana. THE BRYOPHYTA OF ICELAND 449 The entire height of the plant was about G mm. The seta was about 5 mm. high. The capsules were, without the lid, about 0.5 mm. long. 47. Ditrichum homomallum (Hedw.) Hampe. Fl. Dan. tab. 2688, ex Islandia leg. Morch. E. Iceland: Vestdalur near Seydisfjordur!, sterile. N. Iceland: Hof near Eyjafjordur O. I).)!, sterile. W. Iceland : Reykjavik (Grl.;!), fr. ; hot spring near Grafarbakki (F.)!, sterile; Hafnarfjordur, at the bottom of a lava cave!, sterile. S. Ice- land: Geysir! $. Around Reykjavik it was rather common along the side of ditches. There the fruit was ripe on August 7th. Near Geysir it occurred in extensive mats, about 1 — 2 cm. deep, on warm clayey flats with a tem- perature of 35—40°. 48. Ditrichum flexicaule (Schleich.) Hampe. One of the most commonly occurring mosses; it is met with on almost every substratum and at all altitudes. It grows both on damp or soil-covered rocks and in bogs, where it especially occurs woven into the tufts found there, and on damp or on more dry gravelly soil, in lava caves, in grass fields, in heaths, etc. This species varies considerably, especially as regards the length and direction of the leaves. Short-leaved forms (/. brevifolia) are fre- quent on more dry ground, where they form dense tufts with stiffly erect or slightly secund leaves. On damp ground and especially in sheltered localities, for instance among stones, or in clefts, the leaves become longer, often strongly secund, and the tufts higher and looser. Fruit it very rare. Near Seydisfjordur, in the beginning of July, the setae had not developed to their full length and the capsules were barely formed. r 49. Saelania caesia (Vill.) Lindb. Ditrichum glaucescens (Hedw.) Hampe. E. Iceland: Breiddalur!; Hallormstadr!. N. Iceland: Vidimyri (Grl.)!; several places near Eyjafjordur (O. D.;!). W. Iceland: Husafell (Grl.)!; Kalmanstunga (Grl.)!; Gilsbakki!; Hafnarfjordur!; Esja!. S. Iceland: Skal- holt!; common near Thingvellir!. This species is rather common, especially in \Y. and S\V. Iceland, in soil-filled rock and lava clefts, as a rule associated with Miiium orthorrhynchum , Plagiothecium Roeseamim, P. piilchellnm , Pohlia cnula, Distichiam montamim, etc. In the wood by Hallormstadr it was growing on the ground in company with Bartramia ityphylla, Pohlia cruda , Distichinm inclinatnm and Ditrichum flexicaule. The fruit, which is almost always present, ripens in the middle or at the end of June. The plant has not been observed at a higher altitude than about 200—300 metres. 450 A. HESSELBO 50. Distichium montanum (Lam.) Hagen. Distichium capillaceum (Sw.) Br. eur ; Swartzia montana (Lam.) Lindb. Very common all over Iceland. Distichium montanum is one of the most widely distributed mosses in Iceland. It is found everywhere on almost every kind of substra- tum, with the exception of that which is very wet, from the bottom of the valley up to a height of about 500—600 metres above sea-level. At greater altitudes it is more rare, but may nevertheless be met with as far upwards as to the snow-limit, in sheltered localities among stones. This species has its main distribution in the more low-lying regions where, either intermixed with other species or in unmixed tufts, it is hardly absent from any cleft or soil-filled rock-crevice, but it also occurs everywhere intermixed in the moss-covering at the bottom of grass-fields, in bogs, on rocks, etc. The fruit, which is almost always present, ripens in the latter half of July. 51. Distichium inclinatum (Ehrh.) Br. eur. Swartzia inclinata Ehrh. E. Iceland: Vallanes!. N. Iceland: Near Dettifoss!; Husavik!; Hof near Eyjafjordur (O. D.)!; Oxnadalur!; Vidimyri!. NW. Iceland: Gnups- dalur in Dyrafjordur!. It was also collected by Steenstrup, but no habitat is given. Gronlund records this species from Hafnarfjordur, but the specimens in the Botanieal Museum belong to Distichium montanum. This plant was only found in the northern half of Iceland, where it occurred in many places from Vallanes in the east to Dyrafjordur in the north-west, and especially7 in North Iceland proper. It grows as a rule on damp ground, although not very^ abundantly, for instance along streams, associated with Dichodontium, Didymodon rubcllus, Hepa- ticce, etc. Near Vidimyri it was growing along the banks of streams, mixed with Scapania curta, Lophozia Miilleri, Haplozia atrovirens, Di- chodontium and Bryum pattens; near Dettifoss on glacier-sand, in com- pany with Ceratodon purpureus and Aongstropmia longipes and near Husavik on damp sandy soil, with Aongstroemia, Dichodontium and Philonotis tomentelta. In several places it was collected on peaty soil in association with Meesia trichoides, Catoscopium nigritum, Barbula ru- bella, Aongstroemia, Lophozia Wenzelii, etc. In North Iceland proper the fruit was almost ripe at the end of July. 52. Bryoxiphium norvegicum (Brid.) Mitten. Eiistichium norvegicum Br. eur. S. Iceland : Krisuvik (Morch)!; Thingvellir (Morch)!; glacier origi- nating from the Jokul (Stp.)!; Kolvidarhol!; Flokastadagil!; Barkarstadr ! ; Drangshlid!. This species was only found in the south-western part of the THE BRYOPHYTA OF ICELAND 451 country, where it is common in many places and often occurs in enormous quantities. Morch records that it grows in holes in the lava. Near Kolvidarhol it was found everywhere on lull', from the farm (at about 250 metres) up to about 450 metres above sea-level; it was found in extensive mats , especially on the vertical or overhanging sides of the tumbled-down blocks, and in the interior of holes and clefts. It was most frequent on Fljotshlid and south of Eyjafjall. There it was growing in many places on the vertical sides of tuff-rocks in the ravines and on the fallen blocks, for instance in Flokastadagil near Breidabolstadr it covered long stretches of the perpendicular sides of a ravine, from a distance of a few cm. above the water-level of the river upwards, with a dark-green closely adhering mat in which almost no other mosses were intermixed. In this part of the country it has only been met with up to about 100 metres above sea-level. Only ste- rile specimens have been found. Bryoxiphium norvegicnm is the only Iceland moss which does not occur on the European continent or in the British Isles. Outside Ice- land it has only been known to occur in a few localities in North America (Ohio, Kentucky and Wisconsin). FAM. POTTIACE.E. 53. Pottia Heimii (Hedw.) Br. eur. Iceland (Morch)! E. Iceland: Hornafjordur!. N. Iceland: near Eyjafjordur (F.)!; Saudanes (St.)!; Grimsey (O. D.)!. NW. Iceland: Armuli!. W. Iceland: Reykjavik (Grl. ;!); Borgarnes!. S. Iceland: Vestmannaey!. This species grows on sandy or muddy soil near the sea, and is probably commonly distributed along the whole coast in such localities. Around Reykjavik, on Vestmannaey and near Hornafjordur it was com- mon, and was frequently found also on soil-covered rocks and in rock- clefts close to the sea. The fruit ripens about July 1st; on Grimsey the fruit was fully ripe on July 14th, but the lids had not been thrown off. Near Armuli it was hardly ripe during the first days of July. 54, Pottia latifolia (Schwagr.) C. M. N. Iceland: Hof near Eyjafjordur (O. D.)!; Os (O. D.)!, with ripe capsules on June 17th. Note. Pottia triincatnla and P. lanccnlata are enumerated in older lists as found in Iceland, but no specimens of these species are to be found in the collections, and their occurrence in Iceland is very im- probable. 55. Didomodon rubellus (Hoffm). Br. eur. Barbula rubella (Hoffm.) Mitten. Very common everywhere on a more or a less damp substratum, in rock-clefts, on the ground, on rocks and gravelly soil by rivers, in bogs, etc. It grows sometimes in unmixed tufts and sometimes inter- 452 A. HESSELBO mixed with other mosses, and as a rule sets fruit, which ripens late in August or early in September. It is most frequent in the low land up to about 300 metres above sea-level, but is also met with, although scantily, and often sterile, as far upwards as to the mountain heights, for instance on Isafjardarheidi, about 600 metres above sea-level. Forms which must be referred to var. brevifolia Lindb. et Arnell occur commonly together with transitional forms to the type. Near Seydisfjordur the variety was found abundantly in reddish brown, dense tufts, about 5 cm. high, in rock-fissures filled with soil. Note. Didymodon tophaceus is recorded by Lindsay from Ice- land, but no specimens are in the collections and the record is pro- bably due to an erroneous determination. 56. Didymodon rufus Lorentz. E. Iceland: Stafafell!; Geithellir!. N. Iceland: Stadr near Hrutafjor- dur!; Akureyri, at an altitude of 900 metres!. W. Iceland: Lundur! Breidabolstadr in Rej^kholtdalur!. The plant, which was only found sterile, grew in all the above localities in loose tufts, a few cm. high, on damp gravelly ground, as a rule rather scantily. Near Akureyri it grew scantily among Sphcero- cephahis turgidus and Rhacomitrium hypnoides. 57. Leptodontium flexifolium (Dicks.) Hampe. N. Iceland: Grimsey (O. D.)! (f. compacta}. Enumerated in Lindsav's list, but neither the name of the finder t> nor the habitat is given. 58. Trichostomum littorale Mitten. Mollia littoralis (Mitten) Braithw. S. Iceland: Helgafell on Vestmannaey, on blocks of lava!; Hafnar- fjordur, in a lava cave!; on warm clayey flats near Reykjanes light- house (Ostf.)!, associated with Preissia, Riccia and Archidinm. 59. Tortella inclinata (Hedw.) Limpr. Mollia inclinata (Hedw.) Lindb. E. Iceland: Vallanes (H. J.)!. (H). Tortella tortuosa (L.) Limpr. Mollia tortuosa (L.) Schranck. Very common all over Iceland. This species has its main distribution in the low land up to about 400 metres above sea-level. It appears to be rare everywhere at higher levels, and hardly ascends higher than about 600 metres. It grows THE BRYOPHYTA OF ICELAND 453 both on rocks and on earth. In lava-fields it is one of the most com- monly occurring species, and grows there in enormous cushions on rock-sides in caves and clefts, in association with Amphidium Momjotlii, Anocctangiam compactam and Grimmia torqimUt. On rocks it grows on perpendicular faces, on soil-covered ledges, and in clefts. On the ground it is found especially where it is not too damp, for instance in grass-fields and on the top of knolls in bogs, usually intermixed in tufts of other mosses. At higher altitudes it rarely grows on rocks, but as a rule on gravelly ground or in bogs. Only sterile specimens have been found. This species varies considerably in the size and length of the leaves. Forms from shady and protected localities, especially from lava-clefts, form very tall and loose tufts with exceedingly long and strongly crisped leaves. 61. Tortella fragilis (Drumm.) Limpr. Mollia fragilis (Drumm.) Lindb. Commonly distributed all over Iceland. This species growls in localities similar to those of T. tortuosa, and often in company with the latter, but as a rule rather scantily. It usually occurs in unmixed tufts on soil-covered rocks and on some- what damp ground, but only sterile specimens have been found. Around Reykjavik, for instance, it was common on knolls in boggy tracts which had been partially drained. In NW. Iceland it is rather rare, and has only been found in a few localities near Kaldalon. (52. Barbula unguiculata (Huds.) Hedw. var. cuspidftta (Schultz) Braithw. S. Iceland: Vestmannaey !, on damp gravelly soil near the town. It has previously been collected here by an unknown finder H. Jonsson believes by G. Brynj olfs en). W. Iceland : Saurbaer near Hvalfjordur, at an altitude of about 100 metres, on soil-covered rocks. In both places only sterile specimens have been found. 63. Barbula fallax (Hedw.). S. Iceland: Reykir $. W. Iceland: Saudlauksdalur (H. J.). Var. kevi folia n. var. In wide dense cushions, 2—3 inches deep, rusty brown in the in- terior, brownish green at the top. The lower leaves as in the type, the uppermost shortly pointed with rounded, broad and flat apex, into which the strong nerve runs out, widely revolute to near apex, with two deep plicae at the base. Leaf-cells in form and size as in B. fallax, in the lower half of the uppermost leaves, however, more thin-walled, shortly rectangular; all quite smooth or, more rarely, indistinctly papil- lose. The innermost perichaBtial leaves ovate or widely lanceolate, with faint or indistinct nerves. 454 A. HESSELBO S. Iceland: Thorlakshver, on warm clayey ground. Although this form differs somewhat from B. fallax in habit, in the smooth leaves with rounded apex, and in the divergent form of the perichsetial leaves, yet there is hardly any doubt that it must be re- ferred to this species. Setting apart the absence of papillse the leaf- tissue is quite typical, and the form and the plication of the lower leaves are exactly as in B. fallax. It should be remembered that the occurrence on a warm substratum produces very divergent forms also in other mosses, e. g. Philonolis, Catharinea and Oligotrichum. Near Reykir, B. fallax was collected both on stones by the river, in sand- Fig. 1. Bctrbula fallax Hedw. a, Leaves of the plant from Reykir (X 20). b, Leaves of var. Itevi folia ; c, perichsetial leaves of same. filled tufts about 2 cm. high, in a somewhat typical form, and on a warm, damp substratum. Plants from the latter locality form a transitional stage to var. Iwvifolia. It grew in somewhat loose tufts, 3—4 cm. high, which in colour and appearance agreed with var. Icevifolia. The lower- most leaves are pointed, the uppermost rounded; the perichaetial leaves are lanceolate, rounded, with rather faint nerve. The leaf-cells are di- stinctly papillose, sometimes as highly as in the typical form, some- times much more faintly. 64. Barbula cylindrica (Tayl.) Schimp. N. Iceland: Hof near Eyjafjordur (O. D.)!. S. Iceland: Vestmannaey ! ; Ytri Skogur (H. J.)!; Fljotshlid!; Holt!; Drangshlid!; Hornafjordur!. W. Iceland: Esja near Kollafjordur!. This species occurred commonly, and often abundantly, on tuff-rocks in S. Iceland and on Vestmannaey. There it also grew abundantly on sandy soil and on lava blocks near the sea. In the other localities it was found but scantily. Fruit was collected only near Holt, where, at the end of July, both old and yet green capsules were collected from the same tuft. THE BRYOPHYTA OF ICELAND 455 65. Barbula icmadophila Schimp. SE. Iceland : Hornafjprdur!, in several places in small quantities. N. Iceland: Skagafjordur (Grl.)!; Hofsfjall near Eyjafjordur (O. D.)!. W. Iceland: Esja, at an altitude of 400 metres!. This species has been collected everywhere only in small quantities, in cushions 1 — 2 cm. deep, on humus-covered rocks. (»(). Desmatodon latifolius (Hedw.) Br. cur. Tortilla latifolia (Hedw.) Lindb. E. Iceland: Djupivogur!, common near the sea; Vallanes!; Hamar- fjordur!; Berufjordur!. N. Iceland: Husavik! at an altitude of about 400 metres; Reykjahlid!; Grimsey (O. D.)!; Stadr near Hrutafjordur !. NW. Iceland: Isafjordur!; Grunnavik!; Hesteyri!; Arngerdaeyri!; W. Ice- land : Stvkkisholmur!. V Var. inuticus Brid. Grimsey (O. D.)!; Reykjahlid!; Isafjordur!, 450 metres above sea- level. Found in all the localities together with the type. In NW. Iceland D. latifolius is one of the most frequently occur- ring species, and the same appears to be the case in E. Iceland. It occurs especially near the sea on sandy soil or, also, on humus-covered rocks, and often abundantly. Near Vallanes it grew in masses on peat wralls and on dikes around the farm, associated with Encalypta rhab- docarpa, Tortilla subulata, Ceratodon purpnreiis , Brynm argenteiim, Bar- tramia ityphylla, etc. In N. Iceland this species occurs more sporadically. Near Husavik only a single little tuft was found on the top of Husavikurfjall; near Reykjahlid it was common in lava-fields, in places covered by a thin humus-layer, associated with Ceratodon purpnreiis, Tortilla ruralis, T. su- bulata, etc., and near Stadr it grew on the peat walls of the farm ex- actly as it grew near Vallanes. From SW. and S. Iceland this species appears to be quite absent, and in W. Iceland it was only found near Stykkisholmur, where it was found abundantly on earth and rocks along the shore. It is only by exception that Desmatodon latifolius has been found at higher altitudes. Near Isafjordur it occurred here and there on the rocky flat up to a height of about 500 metres, for instance on a stony slope 450 metres above sea-level, associated with Bnjnm eleuans, Bar- tramia ityphylla, Pohlia commutata, Scapania cnrta and Encalypta rhab- docarpa. The fruit, which was present everywhere in abundance, ri- pens at the end of June. 67. Desmatodon cernuus (Hubn.) Br. eur. Tortula cerium (HiibnO Lindb. N. Iceland: Hof (O. D.)!; Hjalteyri (O. D.)!. On the plant from Hjalteyri the fruit had just ripened on Sep- tember 5, 1897. 456 A. HESSELBO 68. Tortula obtusifolia Schleich. S. Iceland: Flokastagil on Fljotshlid!; Drangshlid!. This very rare species was found in both places in very small cushions, only 5—6 mm. deep, with numerous capsules which were al- most fully ripe in the latter half of June. In Flokastadagil it grew here and there on fallen blocks, especially in small fissures on the vertical rock-faces. Near Drangshlid it was found in small quantity on the dry faces of tuff-rocks in company with Tortula mu rails, Grimmia Doniana and Orthotrichum anomahim. 69. Tortula muralis (L.) Hedw. S. Iceland: Vestmannaey !; Drangshlid!. The plant was found very scantily in both places on dry faces of tuff-rocks. On Vestmannaey it grew on a rock-face with a southern ex- posure, associated with Grimmia marlllma and Barbula cylindrical near Drangshlid it grew in association with Grimmia Doniana and Tortula obtusifolia. 70. Tortula subulata (L.) Hedw. Commonly distributed over the whole of Iceland. The plant grows almost exclusively in the low land up to about 300 metres above sea-level, and only in quite a few localities in S. Ice- land has it been found at a higher level, for instance near Barkastadr at an altitude of 410 metres. It is most frequent in S. and E. Iceland; in N. and NW. Iceland it is somewhat less common, but has never- theless been collected from a great number of places. It usually grows on a rather dry substratum, e. g. humus-covered rocks, in rock-clefts, on dikes and on peat walls of houses, mostly associated with Bartramia ityphylla, Pohlia cruda, Encalypta rhabdocarpa, Brachythecium albicans and other species. Fruit, which is always present, ripens in the end of June or in the beginning of July. 71. Tortula mucronifolia Schwgr. Vestmannaey!. It occurs here in localities quite similar to those of Tortula subu- lata, for instance on dikes, in sandy soil and on humus-covered rocks, V and appears to be as frequent as this. The fruit was not yet quite ripe towards the middle of June. 72. Tortula ruralis (L.) Ehrh. Commonly distributed over the whole of Iceland. V Torinla ruralis is a decidedly xerophilous species, and has, there- fore, its widest distribution in the driest parts of the country. In the lava-fields in the interior, for instance around Mvvatn, it occurs abun- dantly; in NW. Iceland it is also more frequent than in the other parts THE BRYOPHYTA OF ICELAND 457 of the country, especially E. Iceland, where it occurs but scantily in many districts. It grows in sandy soil, upon soil-covered rocks and at the base of vertical rock-faces, and is most frequent in the low land. Near Akur- eyri it was found with ripe fruit (20. 7. 190!) . Near Grunnavik in Jokulsfjordur it was found in fruit at an altitude of 270 metres. In Esja it has been collected up to about 420 metres above sea-level. Near Vallanes the fruit was ripe about July 1st. At the coast, near Reykja- vik, it grew abundantly in large tufts which were quite filled with sand. 73. Tortula aciphylla (Br. eur.) Hartm. T.norvegicci ;\Veb.) Wahlb. X\V. Iceland: D \rafjordur!, at an altitude of 150 metres. It grew there in cushions, about 2 cm. deep, on humus-covered rocks. The capsules were quite green on June 17th. The leaf-form, nerve and leaf-hair in these specimens were quite typical, but the cells of the leaf-base were occasionally chlorophyllose towards the margin, forming a more or less distinct border, in which feature it approached Tortula rnralis. FAM. GRIMMIAGE^E. 74. Schistidium maritimum (Turn.) Br. eur. E. Iceland: Hornafjordur!; Hof!; Hamarfjordur !; Djupivogur!. X. Ice- land: Husavik!; Grimsey (O. D.)!. XW. Iceland: Common everywhere along the coasts!. W. Iceland: Stykkisholmur; Hafnarfjordur!; Reykjavik (Grl.;!); by Hvalfjordur (GrlO !. S. Iceland: Vestmannaey !. This plant doubtless occurs everywhere along rocky shores. It is, however, absent from, or only occurs scantily in. the interior of deep, narrow fjords. Thus, around Berufjordur it is very common towards the entrance of the fjord, near Djupivogur, while it is entirely absent from the head of the fjord. As a rule it grows only on rocks quite close to the sea , and up to a height of some 10 metres. More rarely, for instance near Djupi- vogur and on Vestmannaey, it descends to the sandy ground at the foot of cliffs. Fruit is almost always present abundantly. 75. Schistidium apocarpum Br. eur. Grimmia upocarpa Hedw. Subsp. vulgare (Chal.) Loeske. Common over the whole of Iceland. It grows, as a rule, on rather dry rocks, occasionally also in gra- velly soil, but then rarely in any great abundance. It is most frequent The Botany of Iceland. Vol. I, part II. 30 458 A. HESSELBO in the more low-lying parts of the country, but may, however, occasion- ally he met with upwards of 600 metres above sea-level. 7(5. Schistidium apocarpum Br. eui . Subsp. f/racile (Schwagr.) Loeske. Very common. One of the most frequent mosses, and met with from the lowlands up to mountain heights. It occurs, in numerous forms, both on dr}r and on damp rocks, and on more or less damp gravelly soil. On gra- velly flats, especially above an altitude of about 300 metres, it often forms extensive growths. It occurs also very abundantly on tuff-rocks (for instance in Esja and below Eyjafjall in a low, reddish-brown form. Fruit is always present. 77. Schistidium apocarpum Br. eui. Subsp. confertum (Funck) Dixon. E.Iceland: Hof!; Seydisfjordur !. N. Iceland: Husavik, at an alti- tude of about 400 metres!; Reykjahlid!; between Hnausar and La3kjar- mot!; Vidvik (P. Sofoniasson)!, several places near Eyjafjordur (0. D.)!. This form has its main distribution in X. Iceland, where it is rather common; thus, near Reykjahlid it was found abundantly on lava- blocks. It grows by preference on rather dry rock-faces, or upon stones, and has been gathered everywhere in fruit. 78. Schistidium alpicola (Sw.) Limpr. Var. rivMlarte (Brid.) Wahlb. Very common in E., X. and \V. Iceland, more rare in S. Iceland, where it is absent from many localities. This species grows on stones and rock surfaces in rivers, often in great abundance, covering the banks and the stones in the water for long distances. It does not appear to ascend much higher than about 300 — 400 metres above sea-level. The chief reason for its occurring more scantily in South Iceland must be sought in the fact that the water in many rivers is turbid, owing to the glacier-clay carried in them. In this part of Iceland it is met with especially in rivers with clear water, at an altitude of 200- 400 metres, more rarely in the low land. mJ Var. etialj>icol<{ Loeske. Grimmia alpicola Swartz. N. Iceland: Dettifoss!, fr. This form, which in the above locality grew on blocks of basalt at some distance from the waterfall, but nevertheless exposed to the spray, appears to be as rare in Iceland as in most of the rest of Europe. Forms, intermediate between this form and var. rivnlaris, have not been collected. THE BRYOPHYTA OF ICELAND 459 79. Grimmia commutata Hubener. Grimmia ovalis (Hedw.) Lindb. N. Iceland: Myvatnshraun (St.)!. W. Iceland: Budir (H.J.)!. In the supplement to "Isl. Kryptogamflora" (B. T., vol.20, p. 105) Gronlund has recorded G. ovata from Myvatnshraun and G. commutata from Val- lanes and Kolfreyjustadr. But according to the specimens in the Bota- nical Museum in Copenhagen, determined by C. Jensen, the plant from Myvatn is Grimmia commutata and those from the two other localities are G. ovata. Gronlund has. therefore, probablyr confused the two names (G. ovata and G. ovalis) used by C.Jensen. 80. Grimmia Doniana Smith. E. Iceland: Common from Hornafjordur to Seydisfjordur!. N. Iceland: Holar (Grl.)!; Vidimyri (Grl.)!. NW. Iceland: Dyrafjordur!; Gnupsdalur!; DVnjandi!. Common in SW. and S. Iceland. With the exception of N. Iceland, where it appears to be rare, this species is widely distributed in the more low-lying districts of the country7, as it is only by exception that it ascends higher than 200- 300 metres. Near Holt in S. Iceland it has, however, been collected plentifully at about 500 metres above sea-level. It usuallyr grows in small, round tufts on loose blocks, more rarely in wide cushions, irregular in form. In South Iceland proper for instance near Drangs- hlid it occurs also on faces of tuff-rock. The fruit, which occurs everywhere, was hardly ripe even at the end of July. 81. Grimmia alpestris Nees. E.Iceland: Arnkelsgerdi; Eidar (H.J.)!, sterile. S. Iceland : Hafurs- holt!, fr. 82. Grimmia ovata W. et M. Grimmia ovalis Lindb. Iceland leg Morch!. E. Iceland: Kolfreyjustadur (H.J.)!; Vallanes (H. J.)!; Seydisfjordur!; Berufjordur!. N. Iceland: Hnausar in \7atnsdalur !; Reykjaheidi!; Herjardalsheidi (Grl.)!. Only sterile specimens have been found. This species grows on dry stones and rocks; it is rather frequent in East and North Iceland, but has not been found in the other parts of the country. V 83. Grimmia incurva Schwgr. E. Iceland : Vallanes!. It was growing in the above locality on a slightly inclined, partly inundated rock-surface in the river Lagarfljot. 30* 460 A. HESSELBO 84. Grimmia patens (Dicks.) Br. eur. Dryptodon patens Brid., Limpr. E. Iceland: Hornafjordur!. W. Iceland: Budahraun H. J.)!; Hafnar- fjordur !. In Budahraun it was growing in the clefts in the lava-field; near Hafnarfjordur it was found in abundance associated with Orthotrichum rupestre and 0. Sturmii on the face of a dolerite rock with a nor- thern exposure. 85. Grimmia funalis (Schwgr.) Sch. Widely distributed over the whole of Iceland. G. fanalis is by far the most frequent species of this genus. It grows everywhere on dry rocks, especially on the vertical sides of ra- vines and lava-clefts, where it forms immense cushions, often 5—6 cm. deep, which very easily break up into pieces when loosened from the substratum. The fruit, which occurs rather frequently, was not ripe even in August. This species is most frequent up to about 300—400 metres above sea-level, but often ascends, however, to somewhat above 500 metres, for instance near Akureyri. 86. Grimmia torquata Hornsch. E. Iceland: Hornafjordur!, very common; Seydisfjordur !. X. Ice- land: near Hrutafjordur (H. J.)!. NW. Iceland : Dynjandi!; Grunnavik!; Arngerdareyri!. W. Iceland: Melar Grl.)!; Hafnarfjordur Grl.;!); Buda- hraun (H. J.)!. Very common in SW. Iceland!. This species in very common in SE., S. and SW. Iceland, rather rare in N. and XW. Iceland. It grows on dry rock-faces in ravines and lava-clefts, but only sterile specimens have been found. Note. Grimmia puhnnata is enumerated in several older lists, but these records are probably due to a confusion with other species. 87. Rhacomitrium sudeticum (Funck) Br. eur. Grimmia microcarpa (Gmel.) Lindb. Common over the whole of Iceland. In many parts of Iceland R. sudeticum is one of the most frequent species, being found from the sea-level up to the gravelly flats of mountain heights. It is most widely distributed in NW. Iceland and along several fjords in E. Iceland, for instance Seydisfjordur, while it appears to occur less abundantly in N. Iceland. It grows on rather dry rocks and blocks of lava, in clefts, and on wet stones in and by streams. In mountain heights, especially in XW. Iceland, it forms the bulk of the vegetation on gravelly flats from about 300 metres upwards. It varies considerably in size, habit, colour and length of hair point. On wet rocks it becomes very large, and almost black, with very short hair point, while the forms growing on dry rocks are as a rule very low in growth and slender, often occurring in small round, compact tufts, blackish green or brownish red in colour, with longer THE BKYOPHYTA OF ICELAND 461 hair point. In the birch coppices of NW. Iceland a form frequently occurs on larger, scattered stones which, in habit, reminds one of R. fasciculare. The tufts are flat towards the edge, dark-green; the hair point is very short and often wanting. The forms from mountain heights are often jet-black var. atrata} or on damp gravelly flats yellowish green at the top, and grow in extensive, discontinuous mats. a few cm. thick. The fruit, which is very common, ripens in the be- ginning of June. 88. Rhacomitrium heterostichum (Hechv.) Brid. E.Iceland: Hornafjordur!; Hof!; Geithellir!; Berufjordur!. X. Ice- land: Akureyri!, at an altitude of 350 metres. NW. Iceland: Patreks- fjordur!; Arngerdareyri!. Common in S. and \V. Iceland!. Common throughout E. Iceland, from Berufjordur, and southwards through the whole of S. and \V. Iceland. In \V. Iceland it occurs abundantly at the head of Isafjordur, near Arngerdareyri, but has not been collected about the fjord further out- wards towards its entrance; it was also common by Patreksfjordur. It appears to be more rare in N. Iceland. The plant grows most frequently on dry rocks, and more rarely on those that are damp; it occurs in masses, for instance, in the lava districts of SW. Iceland. It is most common in the low land, but is, however, also met with at about 600 metres above sea-level. Fruit is rather common. 89. Rhacomitrium microcarpum Brid. Grimmia ramnlosct Lindb. X. Iceland: Hof by Eyjafjordur (O. D.)!, sterile. Recorded by Gronlund from Reykjavik and Husafell, but the specimens in the Botanical Museum in Copenhagen must be referred to R. canesccns. 90. Rhacomitrium canescens (Weis) Brid. Verv common. •> Next to R. hypnoides the most widely distributed species, and met with as frequently on mountain heights as in the low land, and in numerous forms. It grows both on rocks and on earth, especially \vhere it is somewhat damp. In the "Grimmia heath" it often covers the more low-lying tracts with its light yellowish-green to greyish-green mats, while R. hypnoides grows in the more dry parts, but both species often occur mixed. It is also the most abundant constituent of the vege- tation on damp sandy or gravelly soil by streams, in grass-fields with a poor soil, etc. Forms with the hair point entirely or almost wanting (f. epilosa) are frequent in wet localities. Fruit is only rarely and scantily met with. Near Hof in E. Ice- land plants were found in the middle of June with old capsules, and near Sugandafjordur about July 1st with yet green capsules. 462 A. HESSELBO 91. Rhacomitrium hypnoides (L.) Lindb. Grimmia hypnoides Lindb.; Rhacomitrium lannginosiim (Ehrh.) Brid. Very common over the whole of Iceland. Rhacomitrium hypnoides is by far the most common plant in Ice- land. In all parts of the country, both along the coasts and on the mountain heights, it covers, almost without any mixture of other plants,, vast tracts of land the Grimmia heaths so well-known also from other Arctic countries with its thick greyish -white mats. It also occurs in almost every locality where it is not too damp, and very often intermixed in tufts of other mosses. Thus, it is very common on rocks and stones, and often covers large tracts of lava-fields with cushions one foot deep. In bogs it grows, as a rule, on the top of the knolls, in company with species of Hylocomium, and in birch cop- pices it forms, in association with Hylocomium spp, Hypnnm iincinatum and several other species, the moss carpet of the floor. Only sterile specimens have been found. 92. Rhacomitrium fasciculare (Schrad.) Brid. Very common in the Southern, Western and Eastern parts of Ice- land. In N. and XW. Iceland it appears to be somewhat less plentiful, but nevertheless it must also there be regarded as one of the more commonly occurring species. It occurs at all altitudes up to the limit of vegetation on mountain heights. It forms, there, like R. sudeticum, black Alpine forms on dry rocks. This species usually grows on stones and rocks in dry situations, but it also occurs frequently in gravelly soil. Occasionally it may even be found in the lowermost portion of birch-trunks. The fruit, which is rather common, ripens in the lowlands in the first half of June. 93. Rhacomitrium aciculare (L.) Brid. Very common on wet rocks in and by rivers and waterfalls every- where in the low-lying parts of the country. It does not appear to ascend much higher than 300—400 metres. The fruit, which occurs everywhere, ripens, as a rule, in the beginning of June. Note. Grimmia (Rhacomitrium) elliptica is recorded in older lists as found in Iceland by Morch. The specimens in the collections belong to R. fasciculare. Cinclidotus fontinaloides , also, is recorded by Hornemann as found in Iceland, but it was undoubtedly confused with another species. Specimens are not to be found in the collections. 94. Hedwigia albicans (Web.) Lindb. Hedwigia ciliata Ehrh. SYV. Iceland: Hafnarfjordur (Grl.)!, sterile. THE BRYOPHYTA OF ICELAND 463 FAM. ORTHOTRICHACE.E. 95. Amphidium lapponicum (Hedw.) Schinip. Anaectangium lapponicum Hedw. Very common. This species usually grows on damp rocks, especially in clefts and crevices, but may also occur on a more dry substratum, for instance in lava caves and among stones on heaps of debris at foot of cliffs Urd). It grows both on bare rocks and on humus in rock-clefts, occasionally also in gravelly soil or on earth, and even upon the sides of knolls in bogs. It does not appear to ascend to any great height on the moun- tains; it is most widely distributed up to 200—300 metres above sea- level, but it has, however, been found, although scantily, up to about 500 metres above sea- level. The fruit was usually ripe in the first half of June. 96. Amphidium Mougeotii (Br. eur.) Schinip. Ancectangium Mougeotii Lindb. Iceland (Morch; Stp.)!. E. Iceland: Seydisfjordur!; Stod (H. J. ': Hof near Eyjafjordur (O. D.!); Hrutafjordur (St.)!; M\vatn (Grl.)!. XW. Ice- land: Kaldalon!; Baeir!; Arngerdareyri!; Dynjandi !. West, South-west and South Iceland: common!. Common all over the southern and western part of the country and probably also in NW. Iceland, certainly everywhere north of Isa- fjordur. In N. Iceland it appears to be rarer, but occurs abundantly near Eyjafjordur. In E Iceland it is common everywhere around Sey- disfjordur and is probably also frequent elsewhere. It usually grows in large, thick cushions on damp rock-sides in clefts, and by waterfalls, but is also one of the species most commonly found in lava-caves. This species rarely ascends to any great height on the mountains. In Esja it occurred 400 metres above sea-level, and has nowhere been collected at a greater altitude. Only sterile specimens have been found. 97. Uiota phyllantha Brid. Utota maritime C. M. et Kindb. Weissia maritima Britt. E. Iceland: Everywhere along the coast from Hornafjordur to Be- rufjordur!. NW. Iceland: Frequent around Isafjordur!. W.Iceland: Snre- fellsnes (H. J.)!; Stykkisholmur!; common near Reykjavik, Hafnarfjordur and ever}rwhere around Hvalfjordur!. S. Iceland : Vestmannaey! This species is probably common everywhere along the coasts, where it grows in company with Grimmia maritima quite close to the sea-side. It is only rarely met with at a distance from the sea, as, for instance, around Reykjavik, and in a few places in the lava-fields near Hafnarfjordur. The reason why it has not been collected in North 464 A. HESSELBO Iceland is probably due to the fact that the coast there has been but little investigated. At Husavik the coast cliffs consist of easily weathered tuff which is very poor in mosses, the surface being too much in- clined to crumble away. Grimmia maritima occurred also very sparingly there, and Ulota was not found at all. Like Grimmia maritima it keeps chiefly to the shores of broad fjords; therefore it was not found, or was very rare, in the interior of the deep fjords of East and North-west Iceland, nor did these two species occur at Akureyri. On Vestmannaey Ulota phyllantha was the most commonl}' distributed moss; it occurred abundantly everywhere, reaching up the face of the cliffs and being also found on that side of the latter which faced the interior of the island. It often descended to the ground, it was thus found on the knolls in a wind-torn grass-field on the slopes of Helgafell associated with Rhaco- mitrinm hypnoides and Hylocomiam spp. 98. Orthotrichum anomalum Hedw. S. Iceland: Vestmannaey!; Drangshlid (H. J.;!). On Vestmannaey it was rather frequent on tuff-rocks at the foot of Stora Klit and in Heljusdal. The fruit was ripe in the first days of June. Near Drangshlid it was found on dry tuff-rocks, associated with O. rupestre, Grimmia Doniana and Homalothecium. The plants from this habitat form a transition to 0. saxatile, as slender cilia, which easily fall off, are often found on them. The capsule is however 8-striate, and the diameter of the spores is 0,012—0,018 mm. as in O. anomalum. 99. Orthotrichum saxatile Schimp. SE. Iceland: Hornafjordur!, on rocks in company with O. Stnrmii. The fruit was ripe in the middle of June. 100. Orthotrichum cupulatum Hoffm. S. Iceland: Vestmannaey!, fr. It was growing in the above locality on fallen blocks of tuff at the foot of Stora Klit; in the first days of June it had capsules which had just ripened. In older lists this species as well as 0. affine and 0. lejocarpum is recorded from Iceland as collected by Morch; the habitats are not given more particularly, and no specimens of these species are to be found in the collections, so all the records are probably due to con- fusion with 0. Blyttii. 101. Orthotrichum rupestre Schleich. Common all over Iceland except in the north-west, where it has been observed only at the head of Isafjordur near Arngerdareyri. It grows on dry rocks and detached blocks in the lowlands, and probably does not ascend higher than about 400 metres above sea- level. The fruit ripens in the first half of July. THE BHYOPHYTA OF ICELAND 465 102. Orthotrichum Sturmii Hornsch. E. Iceland: Hof!; Hornafjordur!. W. Iceland: Hafnarfjordur!; near Hvalfjordur!. Growth similar to that of 0. rupestre, and usually found in com- pany with it. Near Hafnarfjordur it was found abundantly on the dry northern face of a dolerite-rock. The plant from Hornafjordur forms in regard to the eight coarse cilia a transition to (). rupestre, but the upper half of the leaf consists of two layers of cells instead of only one in O. rn/)cstre. 103. Orthotrichum Killiasii C. M. E. Iceland: Seydisfjordur!. N. Iceland: Asbyrgi!. W. Iceland: Dala- sysla, Melar on a cliff inhabited by sea-fowl (?) (H. J.)!. The plant from Melar, which was quite sterile, was determined by C.Jensen, but owing to the absence of fruit the determination is doubtful. Near Seydisfjordur, where it grew on rocks close to the sea shore, the fruit was ripe about the 1st of July. 104. Orthotrichum Blyttii Schimp. Iceland (Stp.)!. E. Iceland : Djupivogur!; Seydisfjordur!. N. Iceland : Geitaskard!; Vidimyri (Grl.;!). N\V. Iceland : Arngerdareyri!. W. Iceland: Stykkisholmur! ; Esja (Grl.)!. Grows on rocks, especially near the coast. Thus near Djupivogur Seydisfjordur, Arngerdareyri and Stykkisholmur it wras found abundantly on the rocks of the coast. But it occurs also in the interior of the country; for instance, abundantly in several localities in Blonddalur and eastwards to Vidimyri. Gronlund's specimens are determined by Lindberg as Orthotri- chum arcticum, but on comparing numerous specimens af 0. arcticum and O. Blyttii it has not been possible for me to find any real difference between these two forms. Ha gen (Musci Norvegiae Borealis. p. 83) also regards 0. arcticum as a variety' of 0. Blyttii, from which it is said to differ both by its shorter and broader leaves and by the shorter striae of its capsule; but both these features vary so greatly in the Iceland plants, that there is hardly any basis for establishing variety, still less for separating them into two species. The pericha?tial leaves are usually^ about 2—5 times as long as they are broad, with margins which are revolute from a short distance below the apex down to the base. The capsule is usually striated along its whole length, rarely (as in the plant from Stykkisholmur) in the upper half only. The peristome- teeth are finely papillose, rarely marked with faint sinuose lines in their lower half. 105. Orthotrichum laevigatum Zett. N. Iceland: Grimsey (O. D.)!: Akureyri, 350 metres above sea-level!; Vidimyri!. NW Iceland: Arngerdareyri!. W. Iceland: Kalmanstunga (Grl.)!. 466 A. HESSELBO Like O. Blyttii it grows on dry rocks and in many places in company with this. It has been everywhere collected in fruit. FAM. ENCALYPTACE.E. 106. Encalypta ciliata (Hedw.) Hoffm. Leersia laciniata Hedw. Iceland (Morch)!. E. Iceland: Hornafjordur! ; Djupivogur!; Hof!; Beru- fjordur!. N. Iceland: Ljosavatn!; Tvera in Oxnadalur!. W. Iceland: Stykkisholmur !. Common in South and West Iceland (Grl. ;!). Vestmannaey !. This species has its widest distribution in the southern part of the country, where it is common from Berufjordur in East Iceland and thence southwards and westwards as far as Borgarfjordur. It has not been found in NW. Iceland and it is less frequent in North Iceland. It grows sometimes in small colonies on humus-covered rocks, sometimes in rock-fissures filled with soil, usuallj7 associated with Mnium orthorrhynchnm , Anoectangiiim lapponic.um , Bartramia ityphylla, Pohlia cruda, Distichinm, Mynrella spp. etc. It has its main distribution in the lowlands. In Esja it ascends on exception to about 400 metres above sea-level. In E. Iceland the fruit was quite unripe at the end of June; at Ljosavatn it had just ripened on July 19, but the calyptra still per- sisted. In S. Iceland, also, it ripens in the latter half of July. 107. Encalypta rhabdocarpa Schwgr. Leersia rhabdocarpa Lindb. Common in localities similar to those of the preceding species; it often occurs abundantly also on the peat-walls of houses and on walls. It is met with both near the coast and in the interior of the country v for instance, abundantly at Reykjahlid and is frequent as far up- wards as almost 500 metres above sea-level. The fruit ripens, as a rule, at the end of June, but both overripe and just ripe capsules may frequently be found in the same tuft much later in the year. Var. pilifera (Funck) Br. germ, frequently occurs in company with the type. 108. Encalypta contorta (Wulf.) Lindb. Leersia contorta Lindb. W. Iceland : Budahraun, on lava (H. J.)!, sterile. Note. Encalypta vulf/aris is recorded by Zoega and Morch, and E. commntata by Lindsay, but no specimens of either species occur in the collections. Georgia pcthwida is recorded by Zoega and Vahl as found in Iceland, but of this species, also, no specimens are found in the collections, and all the above records are no doubt due to erroneous determinations. THE BRYOPHYTA OF ICELAND 4(>/ FAM. SPLACHXACE.E. 109. Dissodon splachnoides (Thunb.) Grev. Taijloria lingulata (Dicks.) Lindb. Iceland (Morch)!. E. Iceland: Seydisfjordur. X. Iceland: Common everywhere!. N\V. Iceland: Sugandafjordur!; Isafjordtirl; Armuli!; Arn- gerdareyri!. W. Iceland: Brattabrekka !. S. Iceland: Barkarstadr!, 550 metres above sea-level. Grows on damp boggy ground, almost always mixed with other mosses such as Hypnaceat, (Aiiclidiiim, Mccsia trichoides, Dichodonliiun and Bryum ventricosiim. In N. Iceland, where it is most widely distri- buted, it extends from the lowlands to a height of upwards of 600 metres above sea-level. Thus, near Husavik, it was very common in Hypnum bogs, and near Akureyri it was found especially in bogs at an altitude of 500—600 metres. Near Seydisfjordur it was common from about 100 metres upwards to the mountain heights. From the south- western and southern part of the country it appears to be absent, or is at any rate very rare; it was found in this part of the country only in a Hypnum bog near Barkarstadr, at an altitude of 530 metres. 110. Tetraplodon bryoides (Zoega) Lindb. Tetraplodon mnioides (L. fil.) Br. eur. E. Iceland: Djupivogur!; Berufjordur!. N. Iceland: Akureyri (Car- rington); Myvatn (Grl.)!; Reykir near Svinavatn (Grl.)!; Flateyardals- heidi(St.)!; near Eyjafjordur (6. D.) !. NW. Iceland: Dynjandi!. W. Iceland: Husafell (Grl.)!; Brunnar (Grl.)!; Reynivcllir (Grl.)!; Kolvidarhol! ; Hafnar- fjordur!. S. Iceland: Draupahlid .\Viinsted)!. Occurs here and there all over the country, but as a rule only in single tufts on the bodies of dead animals. Near Djupivogur a large tuft was found on a rotten fish. The fruit, wrhich occurs abundantly everywhere, ripens at the end of June. 111. Splachnum sphaericum (L. fil.) Swartz. Splachnum pedanciilatum (Huds.) Lindb. Iceland (Morch)!; commonly distributed!. Grows on cow-dung in wet, marshy ground, often mixed with S. uas- culosum, but is less frequent than the latter. It occurs most frequently in North Iceland and also, to a certain extent, in East Iceland (Seydis- fjordur and Vallanes), where it is met with abundantly in man}' localities, it is somewhat rarer in South and South-west Iceland and probably does not ascend higher than 300—400 metres above sea-level. The fruit ripens rather irregularly, so that in the same tuft both ripe and also quite young capsules may be found. The majority of the 468 A. HESSELBO fruits ripen during July; near Seydisfjordur many were found to be ripe on July 1st, and in South Iceland ripe capsules were collected between 10—15 June. Splachnum Icnue is recorded byGliemann to have been collected by Morch, but the specimens in the herbarium collected by Morch belong partly to Splachnum sphcericum and partly to S. vasculosiim. i 112. Splachnum vasculosum L. Commonly distributed. Like the preceding species it grows, often abundantly, on cow-dung in wet marsh}r ground. It is most frequent in the lowlands, but ascends also as far upwards as to the mountain heights. Thus at Seydisfjardar- heidi it was common up to about 600 metres above sea-level, and in NW. Iceland also it was found as far upwards as about 500 metres. Such forms from mountain heights are as a rule low in growth and have short setas. As is the case with Splachnum sphcericum the fruit ripens at diffe- rent times during the course of the summer, from the first half of June into August. Splachnum ampullaceum, as recorded to have been found by Koenig, is undoubtedly nothing else but S. uasculosiim. FUNARIACE^:. 113. Funaria hygrometrica L. Commonly distributed all over the country. It usually grows on peaty ground, associated with Dicranella crispa, Polytrichum uracile, P. juniperinum, Bryum spp., etc., but is also found on humus-covered rocks and on tuff. It does not occur abundantly, as a rule, and it does not ascend to any great height, doubtless not higher than to an altitude of 300—400 metres. The fruit ripens in the be- ginning of August. The spores vary considerably in size in this species, from 0.011 to 0.021 mm., in plants which otherwise show no deviation from the type. 114. Entosthodon ericetorum (Bals. et De Not.) Br. eui. Funaria obtusa (Dicks.) Lindb. W. Iceland: Kleppjarnsreykir in Reykholtdalur!; Englandshver!. In both places with ripe fruit (25—30 July). This species grew in the above localities on warm ground. Near Englandshver it grew along the outlet of a spring. Near Kleppjarns- reykir it was found both on a stone standing in water of a temperature of about 50°, mixed with Blimlia acnta, Aneura multifida, Anthoceros and Scapania irrigua, and also on warm, damp ground mixed with Fissidens osmundoides. THE BRYOPHYTA OF ICELAND 469 Note. Entosthodon fascicularis is said to have been found by Hornemann near Reykjavik, but no specimens of it can be found in the collections, and the occurrence of this species in Iceland is not pro- bable. FAM. BRYACE^E. 115. Leptobryum pyriforme (L.) Schimp. Very common in the majority of the districts of Iceland. This species, especially in N. and NK. Iceland, is common on peat or damp ground, but also on rocks, especially in soil-filled fissures. In S. Iceland it occurs abundantly on damp rock-sides, in the clefts of tuff rocks, and by rivers. It is only in N\V. Iceland that it appears to be rarer. There it is common alone; the sea-side around Nautevri and Arngerdarevri, t_* */ mia, Dicranella Schreberi and Bryum inclinatum on peaty flats which had been pared oil'. The fruit was ripe near Berufjordur on June 20th, near Breidabolstadr on July 16th. 135. Bryum Kaurini Philib. E. Iceland: Berufjordur (Grl.)!. The specimens, which are quite typical, were gathered with ripe fruit on July 6th, 1878, and determined by Bcrggren as/?, inclinatum 136. Bryum archangelicum Br. ear. NW. Iceland: Hesteyri!. W. Iceland: Esja (Grl.)!; Brjanshekur (H. J.) !. S.Iceland: Drangshlid (H.J.)!. Both rare and scanty on rather dry, sandy ground or on soil-covered rocks. The fruit ripens at the end of July. 137. Bryum Jorgensenii Kaurin. SW. Iceland: Thingvellir!. The Iceland plant agrees exactly with B. archangelicum in habit. The leaves are narrowly and indistinctly bordered ; the perichaetial leaves have their margins revolute to the apex. The plants are often purely ^; usually, however, a few antheridia and many archegonia are present. In none of the plants investigated did the lamella? show the slightest sinuosity. The spores, which \vere yellow and almost smooth, were of very much the same size as in B. archangelicum. 138. Bryum inclinatum (Sw.) Br. eur. Very common everywhere on a more or less damp substratum, on peat, sand and gravel, on soil-covered rocks, and in rock-clefts. It does not appear to ascend higher than about 300—400 metres above sea-level. Bryum inclinatum varies so considerably in all its parts, in habit and size, in the length of the setae, in the form and degree of inclination: of the capsule, in the structure of the peristome, the size of the spores and in the form and cell-tissue of the leaf, that it is hardly possible to collect t\vo tufts which do not show diversities in one respect or another. Perhaps on a closer investigation many of the forms might possibly be referred to some of the numerous "small .species" established by 31* 47(5 A. HESSELBO Hagen, Bryhn, Ryan, Arnell, Limpricht and other authors, or might with as great justice be described as new species. But without comparison with original specimens, and only according to the descriptions, it is impossible to form any opinion of the value of these species, which have very often been collected only in small quantity, and from a single locality, and which will therefore in many cases prove to be maintainable only so long as there does not exist more than the one specimen. It is very probable that it will not even be possible to maintain as varieties a great many of these forms which have been given specific rank, the characters used for separating the species being so variable that, on having abundant material for investigation, it is impossible to draw any boundary line between the forms. Here, only thorough investigations made at the habitat will be able to throw some light on the influence of the external conditions on the specific characters. The height of the tufts and the length of the stems vary according to the degree of dampness, so that plants from dry and exposed habitats are low in growth with close-set leaves, and from damp localities, as a rule, higher, with elongated stems and more distant leaves. Also in places, slightly illuminated, for instance among grass and Car&r-t lifts, do the plants become higher with elongated stems. The leaves in Brynm inclinatiim, in contradistinction to those in several other species of the same group, are stated to be not decurrent. This feature appears, how- ever, to varv considerablv, and to be closelv connected with the habit •*• »- ' *j of the plant, forms with short stems having close-set, not decurrent leaves, while the leaves on elongated stems are, as a rule, more or less decurrent. In such forms the uppermost close-set leaves have almost always a rounded, not decurrent base, while the leaves further down on the stem become more strongly decurrent the further they occur apart from one another. The form of the cells of the basal angles of the leaf also vary greatly according to the position of the leaf on the stem. The not decurrent leaves have a rounded base with quadrate, somewhat widened and thin-walled cells, but as the leaves downwards become more and more decurrent, the cell-form becomes elongate rect- angular. The leaf-form varies from narrow-lanceolate to almost ovate, with a shorter or longer point. The lower leaves are usually shorter and broader, and the nerve vanishes just below the apex. The leaf- margin is revolute to the apex, more rarely it is plane in the upper part. The form of the leaf-cells is partly dependent on the leaf-form, long, narrow leaves having elongated cells, while broad, short leaves have broader cells, and even in leaves of the same plant the cell-form may vary considerably. The cell-walls vary somewhat in thickness. Xero- philous forms have often thick cell- walls, while bog- forms with large, broad leaves have thin-walled cells. The capsule varies in form from obovate to elongate-ovate. The neck of the capsule is usually straight, more rarely slightly curved. The peristome teeth vary in colour from pale yellow to brownish yellow, being very strongly coloured where inserted. The "insertion" may be very differently developed, all transitions are met with, from a slightly indicated yellowish-brown or orange ring at the base of the peristome teeth to a highly developed compact thickening (fundus) THE BRYOPHYTA OF ICELAND 477 \vhich may be almost as large as, for instance, that in B. rclnsiim. It is, however, not usual for the thickening to he distinctly localized around the base of each individual peristome tooth; it has more the charac- ter of a continuous ring, 0.02—0.07 mm. broad. Hagen (Musci Xorv. Bo- realis, p. 141) pronounces the opinion that ultimately all the species with a distinct fundus will be united together in a separate group in a na- tural system of species of Brynin (Brya hcemotostomata). The feature in question appears, however, to be too variable for that purpose. It is especially in the group of forms of inclinatum that this peculiar de- velopment of the peristome base occurs, but it is also met with in other groups, although less frequently, for instance in B. pnrpnrascens where it may be almost as large as in Brya hcemotostomata Hagen) and in B. uliginosum. B. ciirvatnm Kaur. & Arnell, which Hagen refers to B. hcematostomata, also belongs to the piirpnrascens p aliens group. On the other hand, forms mav also be met with in which the fundus is t/ rather slightly developed or even quite wanting, for instance B. Kan- rim, B. retnsnm and B. Graefiannm, referred by Hagen to B. hcemato- slomata. This diminishes the value of the character in question, and it does not appear to have greater systematic importance than has* the peculiar structure of the lamellae for the group Hemisynapsium, which structure is especially met with in the group of species in which the fundus formation occurs. Both the fundus formation and the indentation of the lamellce, as also the occurrence of perforations in the median line of the peristome teeth, are probably connected with certain external influences, and are very often met with together. Here it is especially the degree of salinity of the substratum which is of importance, aula- codonte peristomes being found almost exclusively in Brynm forms collected from localities close to the coast, while forms with a distinct fundus-formation, although most frequent in the vicinity of the sea, \ret have also been found far inland, or at a height of 400—500 metres above sea-level. In Iceland indented lamella? and peristome teeth more or less perforated in the median line have been observed in forms of B. inclinainm, B. retnsnm, B. archangelicum, B. calophyllnm and B. pnrpur- ascens, in the last-mentioned species, however, the peristome teeth are never perforated. The spores vary somewhat in size, most frequently 0.022—0.025 mm., more rarely as much as 0.029 mm. Brynm lapponicnm Kaurin has not been found in Iceland, but forms which approach this species by having broader and longly decurrent leaves are rather frequent. 139. Bryum retusum Hagen. N. Iceland: Hnausar in Vatnsdalur!; Yidiimri!; W. Iceland: Stykkis- holmur!; Borgarnes!. This species grows on peat or soil-covered rocks. The capsules ripen in the beginning of July. Near Stykkisholmur they were almost ripe on June 15th. In all the plants referred to this species the leaves were shorter and broader than in B. inclinatum, with the nerve vanishing in the apex and shortly excurrent in the perichaetial leaves. The capsule 478 A. HESSELBO is narrower than in Bryum inclinatnm, not-glossy, dark brown, finely pitted (in B. inclinatnm smooth and glossy), with a high and conical lid. The peristome teeth are narrow, dark yellow, with a very large, red fundus which is very easily loosened from the mouth of the capsule and falls off together with the peristome tooth belonging to it, equally wide to the middle or gradually taperi::g from the base, and very differently formed in the same peristome. Lamellae 12—18 in number, very differently developed even in the same peristome, straight or sinuous. frequently also porous in the median line af the teeth. The spores vary somewhat in size, from 0.020 mm. (Borgarncs) to 0.024—30 mm. (Vidi- myri). 140. Bryum islandicum n. sp. Gaespites densi ad 5 — 6 mm. alti. Caulis ruber, fragilis, valde to- mentosus , innovationibus brevibus. numerosis. Folia caulina inferiora decur- rentia, 1.5 mm. longa et 0.7—0.9 mm. lata, superiora non vel vix decur- rentia, ovata, longius cuspidata, api- cem versus parce denticulata, 2 — 2.2 mm. longa et 0.75 mm. lata, ad basin rubra; margine tota longitudine reflcxa, seriebus 3—4 ccllularum angustiorum . limbata. Cellulas lep- todermes paulum porosse, basilares rectangula2, 0.03—0.04 mm. longse et 0.02 mm. latae, ceterce elongato hexa- gonse. 0.03—0.04 mm. longre et 0.015—0.018 mm. lata. Costa ad inscr- tionem rubra, in aristam longam excurrens. Folia perichaetialia intima anguste lanceolata, vix limbata, costa excurrente longiuscule cuspidata. Inflorescentia synoica; anthcridia et archegonia numerosa. Seta ad 15—20 mm. longa et 0.16 mm. crassa, rubra. Capsula pendula, deoperculata ca. 3 mm. longa et 1 mm. crassa, opaca fusca leptodermis, sicca leviter rugulosa. Operculum humile conicum. Annulus latus. Cellule exothecii leptodermes, marginales in series 3—4 transverse rectangulrc-polygonas quadratas, cetera? irregulares. Exostomii dentes e fundo fusco-aurantio 0.4 mm. longi et 0.065 mm. lati, fusco-aurantii apice lutei, anguste limbati, subtiliter punctulati. Lamelhe 14—16, inter sc liberyc, marginibus integris. Endostomium exostomio haud connatum, luteolum, parce papillulosum ; processibus lanceolatis, in carina ovaliter fenestratis, ciliis pro more rudimentariis. Sporse 0.039—0.038 mm. diam. olivaceae, punctulatse. N. Iceland: Akureyri, on damp ground at an altitude of about 300 metres, July 20th, 1909. Fig. 2. Bryum iftlandicum (X 2). THE BRYOPHYTA OF ICELAND 479 141. Bryum calophyllum R. Brown. E. Iceland: Vallanes!, on wet boggy ground. The capsules were quite green even on June 27th. Fig. 3. lirijum isliindicntn. a. Leaf margin (X 1-0); b and c, pericha-tial leaves: d and e. leaves. 142. Bryum uliginosum (Bruch) Br. eur. N.Iceland: Husavik!; Svinadalur!. W. Iceland: Haukadalsheidi!5 at an altitude of about 300 metres. In all the above localities it grew abundantly on dam]), sandy ground. On Haukadalsheidi the fruit was ripe on Aug. 1st, in the other localities it was unripe in the middle of July. Besides <$ and ^ flowers, a few hermaphrodite flowers also occur fre- quently. The papillae of the peristome are in the lowermost transverse seg- ments often distinctly arranged in transverse rows, and sometimes there are also distinct transverse bars as in B. piirpnrascens. As is the case in the latter species, the ripe capsule contains a colouring matter which on being treated with ammonia assumes a red colour in the air. 143. Bryum Groenlundii n. sp. Csespites laxiusculi, ca. 1.2 cm. alti, superne virides, subnitentes; sur- culi innovationes tenues. ! ^ \VX^ •-. ijj. 4. Hryum islandicum. Peristome (X 120; phot.). 480 A. HESSELBO Folia caulina decurrentia, inferiora ovata, breviter cuspidata, superiora longius cuspidata, breviter vel non decurrentia, 2.3 mm. longa et 0.9 — 1 mm. lata, apice integra vel leviter dentata; margine ad apicem reflexa, seriebus 2—4 cellularum angustiorum limbata. Cellulae foliares leptodermes, indistincte porosae, basilares rectangulae, 0.035—0.050 mm. longae et 0.018—0.020 mm. latae, ad insertionem rubrae; illae folii medii elongato-hexagonae, vel rhomboideae 0.05—0.08 mm. longas et 0.015- 0.018 mm. latse, apicales angustiores. Costa fusco-lutea, ad insertionem 0.08 mm. lata, in foliis inferioribus sub apice desinens. in superioribus in cuspidem integram excurrens. Folia perichsetialia intima anguste triangula, margine limbata. Inflorescentia synoica; an- theridia perpauca; archegonia et paraphyses numerosae, roseae. Seta 3 — 4 cm. longa et 0.20 mm. crassa, rubra. C a p s u 1 a nutans, arcuato-clavata deoperculata 3. 35 mm. longa et 1 mm. crassa, sub orificio obliquo rubra contracta; collum 1.5 mm. longa. Oper culu m humile conicum, apice rubro. Annul us 0.14 mm. latus, triplex. Exostomii dentes e fundo purpureo vel rubro-aurantio bene definite 0.40—0.45 mm. longi et 0.10 mm. lati, fusco-lutei, anguste limbati, dense et subtiliter papil- lulosi; lamellae ca.24, inter se liberae, margine integra. Endostomium exostomia vix adhaerens, luteum, subtiliter papillulosum; processus dentibus aequilongi, fenestrati; Cilia nulla. Sporae olivaceas, 0.025-0.033 mm. di a metro, punctulatse. damp gravelly ground at an altitude Fig. 5. Bryum Grcenlundii (X 3). W. Iceland: Haukadalsheidi on of about 350 metres, August 1st, 1909. 144. Bryum fallax Milde. N. Iceland: Geitaskard!, fr. It was growing here in a dried up pool among Pohlia temiifolia. 145. Bryum oeneum Blytt. Bnjnm nitihms Brid. E. Iceland: Djupivogur!; Seydisfjordur!; at an altitude of 400 metres. N. Iceland: Akureyri!, at an altitude of 350 metres. NW. Iceland: Bildu- THE BHYOPHYTA OF ICELAND 481 dalur (C. Hansen)!. NW. Iceland : Lundur!, fr. S. Iceland: Vestmannaey! ; fr. ; Skalholt!; Austerhlid near Geysir!; Breidabolstadr ! ; Barkarstadr!; Holt!, fr.; Drangshlid!. Common in the southern part of the country and on Vestmannaey; rarer in the other parts of the country. In S. Iceland it grew especially l-ig. 6. Bryum Grcenlundii. «, Capsules (X20); /», leaves (X20); c, perichc-etial leaves (X20); (/, leaf margin at base, and e, from the middle of Ihe leaf ()\ 120). abundantly everywhere in clefts of tuff rocks, and on Vestmannaey it •/ «J ». was also frequent on the faces of damp tuff rocks. It was found in several localities in fruit, which was quite green even in the beginning of July. Near Lundur it was found on damp ground, associated with other Bryum spp. and Dichodontinm, and had ripe fruit at the end of July. In several of the fruiting specimens from this locality a few hermaphrodite flowers were found besides the numerous $ flowers. $ plants occur everywhere, but J1 plants have not been found. In the leaf-angles of all the plants investigated hair-formations were found, consisting of readily falling, 8—10 celled, brown, papillose hairs, which very easily break into pieces of 2—4 cells. The leaves vary from shortly pointed, with nerve vanishing just below the apex, and shortly 482 A. HESSELBO rhomboid, equilateral-hexagonal or almost quadrate cells (forms from AkureyrD, to more or less longly pointed, with excurrent nerve, and narrower, rhomboid or elongate-hexagonal cells. 14(5. Bryum bimum Schreb. E. Iceland: Vallanes. It has been collected only «/ scantily on damp ground, with capsules which were not ripe at the end of June. Two sterile Brya, collected by Helgi Jons son near Stod in E. Iceland and in Budahraun, are referred to this species by C. Jensen. The leaves in both the plants taper to a long point, are longly decurrent, have nar- row basal cells, and the nerve excurrent; therefore, the plants probably belong to Firynm uffine, but owing to the absence of fruit the determination is quite uncertain. 147. Bryum affine (Br'uch) Lindb. Bryum cuspidcitiim Schimp. Commonly distributed. One of the most frequent species of Bryum, and occurs everywhere in the lowlands on damp sandy or peaty ground, and on humus-covered rocks. The fruit ripens in the first half of July. It varies exceedingly in all its parts. It is said to differ from the very nearly allied B. cirratnm in its sex, the smaller, smooth spores, and the decurrent leaves with the broader cells; but all these features are so variable that in reality it is hardly possible, at least in the Arctic- countries, to separate these two species. The plant is usually synoicous, but $ flowers are also almost always present; $ flowers are more rare. The spores vary in size from 0.008 to 0.020 mm., and often differ rather considerably in size in the same capsule, or in different capsules from the same tuft; the most frequent size is 0.012—0.017 mm.; they are sometimes smooth, sometimes finely papillose. The leaves vary in form from about ovate to lanceolate, tapering more or less to a long point, and with the nerve longly excurrent. In form the leaf-cells correspond nearly with the leaf, so that short leaves have broader cells than have those which are long and narrow. Fig. 1. Bryum Grcenhmdii. Peristome (X 250; phot.). THE BRYOFHYTA OF ICELAND 483 The leaf-base, at any rate in the lower leaves, is Recurrent, with elongated, narrow alar cells. The close-set uppermost leaves are usually not decurrent, and then have the base rounded, with quadrate, some- what widened alar cells. The structure of the leaf-base evidently depends on the degree of dampness of the habitat. Brynm cuspidalnm usually grows on boggy ground and forms here tufts, 1—3 cm. high, with rather long innovations. On such elongated shoots the leaves arc always decurrent. On a more dry and exposed substratum, for instance on rocks, the tufts become lower in growth and denser, and then the leaves are only slightly, or not at all, decurrent, and in connection with this the alar cells are short as in Brijum cirratum. 14cS. Bryum cirratum Hoppe et Hornsch. Rather common. Grows in drier localities than does B. affine, for instance in gravelly soil, on slopes and among grass. It is especially common in N\V. Iceland, and occurred abundant!}7 for instance on stony slopes near Dyrafjordur. The forms which are here referred to 71 cirratum have 9, $ and numerous J1 flowers. The leaves are not decurrent, taper to a very long point, with narrow, almost linear cells in the upper portion. The spores are 0.014— 0.020 mm., yellow, and finely papillose. Brijum affuic and B. cirratum form a continuous series of forms, in which 13. afftnc represents the h}Tgrophilous and B. cirratum the xerophilous adaptation-form. 149. Bryum intermedium (Liuhv.) Brid. N. Iceland: Grimsey (O. D.)!; VidimVri!; Stadr near Hrutafjordur !. S. Iceland: Merkjafoss (F.)!. Rather rare and scanty on damp soil. Near Stadr the fruit was ripe on August 1st, but the lid still persisted. 150. Bryum pallescens Schleich. Widely distributed. One of the most frequent species everywhere up to a height of about 300 metres above sea-level. It usually grows on damp rocks, where it often forms very large and deep cushions, with numerous capsules; but it also occurs on damp soil. In South Iceland it is very common everywhere on faces of tuff rocks. The plant is, as a rule, monoicous, but very often hermaphrodite flowers are also met with, containing many antheridia and a few archcgonia. 151. Bryum subrotundum Brid. S. Iceland: Uxavatn (T.)!. 484 A. HESSELBO 152. Bryum capillare L. E. Iceland: Hamarfjordur!. N. Iceland : Modrufellshraun (St.)!; Grimsey (O. D.)!. W. Iceland: Hvammur (Grl.)!; Hafnarfjordur!; Videy!, several places near Reykjavik!. S. Iceland: Breidabolstadr !; Holt!. Vestmannaey !. This species occurs, as a rule only sparingly, on humus-covered rocks and in lava-clefts. Only on Vestmannaey was it common, occur- ring especially on the tumbled-down blocks at the foot of cliffs inhabited by sea-fowl. The nerve usually vanishes just below the hair-shaped leaf-point. In the plant from Modrufellshraun and in the majority of the specimens from Vestmannaey the nerve varied considerably in length, sometimes reaching scarcely beyond the middle of the leaf, sometimes almost to the apex. The plants from the former habitat, in addition, bore clusters of easily falling brown threads in the uppermost leaf-angles, quite similar in appearance to those in Rnjnm oenenm. 153. Bryum csespiticium L. Iceland (Krabbe, 1863:!. E. Iceland: Seydisfjordur!; Vallanes (H. J.;!); Hallormstadaskogur !. N. Iceland: Halsskogur!; Stadartunga (O. D.)!; Vidvik (P. Sofoniasson)!. S.Iceland: Almannagja!. Gronlund records this species from Reykjavik and Laugardalur. but there are no specimens of it from these localities in the collections. Grows in dry sandy soil, especially in birch coppices, and appears to be rather frequent in North and East Iceland. It occurred abundantly in several localities in Halsskogur. Near Vallanes it occurred sometimes on dry sandy soil, sometimes on the dikes and peat-walls of the farm. In Halsskogur the fruit was ripe on July 19th, but some of the lids still persisted. 154. Bryum comense Schinip. N. Iceland: Reistarargil (O. D.)! ?; Hof (St.)!. Both the above localities are situated on the east side of Eyjafjordur. 155. Bryum elegans N. v. Es. E. Iceland: Djupivogur! rafj6rdur northwards!. W. Iceland: Frodarheidi (H. J.)!; Esja, many places!. S. Iceland : Selja- land (Stp.)!. Grows on inundated ground, as a rule in the water itself, for in- stance along streams and in moss bogs. In NW. Iceland it is one of the most frequently occurring species. and is met with abundantly up to a height of above 400 metres above sea-level. It often forms in association with Pohlia albicam, Scapania uliginosa, Haplozia cordi folia and Chiloscyphus polyanthus v. fragilis the main portion of the moss-carpet along streams. In the other parts of the country with the exception of S. Iceland where it has been found only near Seljaland - - it is rather common. It is usually met with from about 250 to 500 metres above sea-level, but frequently ascends up to about 600 metres, for instance by Berufjordur. The fruit, which was quite green even in the first half of July, has been found only in a few localities in the district of Isafjordur and near Eyjafjordur, and only scantily. 191. Philonotis tomentella Mol. P. dlpicola Jur. Widely distributed over the whole of Iceland. P. tomentella usually prefers drier localities than does the closely allied P. fontana. In N. Iceland, where it is very common, it grows abundantly everywhere on partially dry, grass-covered ground, and is easily distinguished from P. fontana by its more slender growth and by the extremely dense tufts, with stems covered with brown tomentum */ almost to their summit. It grows, also, both on rather dry and on damp rocks and on wet boggy ground in company with P. fontana, with- out, however, extending into the water itself. It varies very considerably in habit and size. The leaves are more or less falcato-secund, and forms especially from dry rocks have leaves strongly falcato-secund (f. falcatd). In shady localities, for instance in rock-clefts and caves, slender to almost thread-like forms (var. capillaris) are frequently met with. Forms growing in bogs are more vigorous than are those growing on a drv substratum, and are also less densely o o «-• tomentose. On damp rocks and in humus-filled rock-clefts there frequently oc- curs a slender form with numerous slender, easily falling branches which probably serve for vegetative propagation (f. flagellifera). Limpricht (Kryptogamenflora, vol. II. p. 573) records that the THE BRYOFHYTA OF ICELAND 497 cortex in this species consists of 3 — 4 layers of sharply defined, small stereids covered with a sphagnoid outer cortex, while P. fonlana has not a sharply differentiated cortical layer. This feature appears, however, to be closely connected with the degree of dampness of the habitat, so that forms from a dry substratum, both of P. tomentella and of P. fon- tana, have several layers of thick-walled cortical cells, while bog-forms have thin-walled cortical cells, and (as in Dicramim scoparium and D. angnstiim] all possible transitions may be found between thin-walled and thick-walled cortical cells. Fruit occurs very frequently and ripens at the end of July or in the beinnin of Auust. FAM. TIMMIACE.E. 192. Timmia norvegica Zett. E. Iceland: Hof!; Vallanes (H. J.)!. N. Iceland: Pollar (St.)!; Akureyri!, at an altitude of 300 metres; Hof near Evjafiordur O. D.)!; Vidimvri */ *f u * (Grl.)!. S. Iceland: Vestmannaey!. It grows on earth and in rock-clefts, but has been collected every- where only scantily. Near Hof (E. Iceland) it grew on gravelly ground in association with Oncophoms virens, Ditrichnm flexicaule, Myurella jnlacea and M. apiculata at an altitude of about 150 metres. Near Akureyri it was found sometimes in rock-clefts, in company with Mniiim orthorrhynchum, sometimes on rocks mixed with Philonotis tomentella. Only sterile specimens have been found. 193. Timmia austriaca Hedw. Very common especially in N. and E. Iceland, but more rare in NW. Iceland (Dyrafjordur, Isafjordur, Grunnavik!). It grows on earth or on soil-covered rocks, and often in masses. Thus in several places in Hallormstadaskogur it was the most abundant member of the moss- carpet under the birches, especially on knolls and soil-covered stones. In several places in N. Iceland, for instance in Oxnadalur, it covered the slopes along streams, often greatly mixed with other species. Timmia austriaca is most frequent in the lowlands up to a height of about 300—400 metres, but is also often found on mountain heights (for instance on Seljaland at an altitude of about 620 metres) although usually in small quantity. Fruit has been found only near Tvera and Vidimvri in N. Iceland; it occurred plentifully in both places and had just ripened at the end of July. FAM. POLYTRICHACE^E. 194. Catharinea undulata (L.) Web. E. Iceland: Hornafjordur!; Lon!; Berufjordur!. N. Iceland: Hof near Eyjafjordur (O. D.)!; Reykir near Svinavatn Grl.)!. W. Iceland : Reykja- 498 A. HESSELBO vik (Morch;!); near hot springs in Reykholtdalur (Grl. ;!); BorgarfjordurL Common in S\V. and S. Iceland!. Commonly distributed in SE.. S. and W. Iceland from Lon in the south-east to Borgarfjordur in the west. In N. Iceland it has been found only near Eyjafjordur, and it has not been collected in XW. Iceland. It grows sometimes on peat, sometimes on damp clayey ground, for instance by sides of ditches, and is occasionally found in f fruit, which about Reykjavik was quite undeveloped even in August. It is a de- cidedly low-land species, and has not been found at a higher elevation Fig. 9. Catharinea nndnlata (L.) Web. var. thermophila (nat. size). than 50 — 100 metres above sea-level. The usual forms of this species are low in growth, 1—2 cm. high, with leaves which are as a rule 4—6 mm. long, narrowly lanceolate, obtuse or shortly pointed, only slightly undulate with a few spines at the back, and the margin often with single teeth. Catharinea undnlata is one of the species which is found most fre- quently and abundantly on warm ground, where it occurs in rather divergent forms. Usually it resembles the southern woodland forms with long, strongly undulating leaves, very rough at the back. A very peculiar form is Var. thermophila n. var. Loose cushions as much as 10 cm. high. Leaves evenly distributed along the whole length of the stem, or somewhat denser at the top, often falcato-secund, 6—7 mm. long, linear-lanceolate, sharply pointed, with 4—5 lamellae at the back. Lateral shoots are often developed along THE BRYOPHYTA OF ICELAND 499 the stems. This form grew abundantly near the hot springs about Skalholt, especially on the slopes stretching down towards the outlets of the springs. 195. Oligotrichum hercynicum (Ehih.) Lam. Oligotrichnm incurviim (Huds.) Lindb. Iceland (Morch). E. Iceland: Seydisfjardarheidi!. N. Iceland: Ljosa- vatn!, common 350 metres above sea-level and upwards; Askja (Caroc)!. NW. Iceland: Very common!. \V. Iceland: Stadarfell ;Stp.); Esja!, at an altitude of 400 — 500 metres; Reykholtdalur (Grl.;!); Hafnarfjordur!. S. Iceland: Common from about 350 metres and upwards!; Krisuvik (Stp.)!; everywhere near hot springs!. This species has a very peculiar distribution in Iceland. It has its main area of distribution on the mountain heights, where it doubt- less occurs over the whole of Iceland, and often in masses. It grows here on damp gravelly flats, especially in the neighbourhood of the snow-patches, in association with Anthelia Jarat-kana, Pleiiroclada albes- cens, Pohlia gracilis, Polytrichum sexangalare, etc., and as a rule sets fruit. Scarcely anywhere has it been found until at a height of 350- 400 metres, and was most abundant at about 500 — 700 metres above sea-level. Only in NW. Iceland, where it is exceedingly common, did it descend to a lower altitude, in man}7 places as low as to the sea-level. In the greater part of the country it is quite absent from the low land; in SW. Iceland it has been found only scantily in a lava cave near Hafnarfjordur. This species has another area of distribution near the hot springs in SW. and W. Iceland. Here it has been collected near a great number of springs in Reykholt- and Reykirdalur, around Skalholt and in several other places, where it often occurs abundantly on the warm clayey flats, but only sterile. These warm-soil forms differ somewhat from the Alpine forms. As a rule they are quite low in growth, about 5—10 mm. high, with softer leaves, twisted or incurved when dry, with a few (5—6) lamellae at the back. The leaf-cells are more thin-walled, chlorophyllous, larger and more regularly quadrate and transversely elongated, usually 0.015—0.018 mm., but occasionally also 0.025 mm. in diameter, shortly rectangular at the base, 0.018 mm. broad. The nerve is often only half as broad as in the Alpine form. Such forms grow especially on the warm clayey flats, in company with Anthoceros, Fossombronia, Haplozia crenulata and other hepatics. Near Deildartunguhver in Reykholtdalur it grew on the warm ground among other mosses, in tufts about 3 cm. high. Forms exactly resembling the Alpine forms occur also frequently on the warm ground. In the majority of the localities in NW. Iceland the fruit was ripe in the latter half of June, on the mountain heights early in July. 500 A. HESSELBO 196. Psilopilum laevigatum (Wahlb.) Lindb. Oligotrichum glabratum Lindb. O. Icevigatum Br. eur. Psilopilum arcticum Brid. E. Iceland: Hornafjordur!; Berufjordur!; Seydisfjordur!. N. Iceland: Husavik!; Akureyri!; Hof near Eyjafjordur (O. D.)!; Geitaskard!. NW. Iceland: Isafjordur!; Snsefellsstrond ! . W. Iceland: Stykkisholraur ! ; Stadar- fell (Stp. !; Hafnarfjordur!; Reykjavik (Morch; Ho.; Stp.;!). S. Iceland : Common in Olfns!. Commonly distributed everywhere near the coasts. It grows there on rather dry peaty ground, and often in great abundance. For instance near Reykjavik it covers in association with Dicranella crispa, Bryum pallens, Scapania curia, etc. large tracts of ground on the peninsula. It appears to thrive more particularly in drained bogs whence peat is being cut; thus around Husavik, Akureyri and Isafjordur it occurred in very great abundance, partly on the ground and partly on the piled up heaps of cut peat, which were often quite covered by it. Funaria hygrometrica and Pogonatum iirnigerum often occurred abundantly in company with it. Fruit ripens in the beginning of (Reykjavik) or at the end of June (N. Iceland). Note. F. Ha gen in his preliminary works on a Frondose-Moss Flora of NorwajT (XIX, Polytrichacece) supposes that Psilopilum tschiictschicum (Mull. Hal.) Par. has been collected in Iceland by W. F. Hooker. All the specimens I have had an opportunity of investigating, both numerous older specimens collected by Morch, Krabbe, Gronlund and others and my own specimens collected in a considerable number of habitats from all parts of Iceland, belong to Psilopilum Iwuigatum, which is doubt- less the only species of this genus found in Iceland. 197. Pogonatum polytrichoides (L.) Brockm. Pogonatum nanum (Schreb.) P. B. P. siibrotundum Lindb. Iceland (Ho.; Morch)!. W. Iceland: Reykjavik (Grl.;!); Stykkisholmur (Stp.)!: Sletta (Stp.); in the district of BorgarfjordurL S. Iceland: Near the Thjorsa ;Stp.)!; frequent in Olfus!. This species was found only in SW. and W. Iceland, but was rather common in both places on somewhat damp and especially peat}7 soil, for instance by the sides of ditches and along roads. In the district of Borgarfjordur it was common along roads. Around Reykjavik it was found everywhere by the sides of ditches. Fruit was found everywhere, the capsules were partly old specimens from the previous year and partly such as were quite young even in August. Note. Pogonatum aloides (Hedw.) is recorded to have been collected by Stecnstrup near Sletta, Stykkisholmur and the Thjorsa. but all the specimens belong to P. polytrichbid.es. THE BRYOPHYTA OF ICELAND 501 198. Pogonatum dentatum (Menz.) Brid. Var. minus (Wahlb.) Hagen. Reykjavik !. Here it grew in several places on peaty soil, and in one place very abundantly, with numerous capsules, some of which were almost ripe in the first half of August. 199. Pogonatum urnigerum (L.) P. B. Polytrichum urnigerum L. Widely distributed over the whole of Iceland. Grows usually scattered as individual plants, or a few plants to- gether, among other mosses on dry, humus-covered rocks or on the ground, both dry and somewhat damp; for instance along the banks of streams. It occurs in large quantities on peat, often forming large light- green patches, interwoven with Alicularia scalaris and, occasionally, Sca- pcinia ciirta. On somewhat damp, moss-grown slopes it often forms large tufts several centimetres high among Hylocomium spp., Hypnum uncinatum and Polytrichum alpinum; such vigorous forms are also fre- quently met with in South Iceland on somewhat damp ground, for in- stance by the sides of ditches. It is most frequent in the lowlands and does not appear to ascend above 300 — 400 metres. The fruit, which only occurs on large plants growing in tufts, was ripe or overripe in the beginning of June. 200. Polytrichum alpinum L. Ver3r common everywhere both on dry and on somewhat damp ground, and almost equally frequent from the sea-level up to the limit of vegetation on mountain heights. It grows both mixed with species of Hylocomium and interspersed in Rhacomitrium-mais on knolls in bogs, on peat, in grass-fields and on the stony slopes of mountain heights. The fruit, which occurs very frequently, ripens in the lowlands about August 1st. Varies considerably in habit, length of leaf, form of capsule, etc., but the majority of the forms, however, approach closest to the type. Forms agreeing more or less with var. septemtrionale (Sw.) Brid. are also common. 201. Polytrichum formosum Hedw. W. Iceland: "Steluhusid" in Sokkolfdalur (F.)!, sterile. 202. Polytrichum gracile Dicks. Rather common over the whole of Iceland. This species grows in peaty soil, often abundantly, and sets fruit almost always. It occurs only in the low land and has hardly been 502 A. HESSELBO found at a higher level than 200—300 metres. Near Akureyri the fruit was ripe at the end of July. Var. anomalum (Milde) Hagen. Hof near Eyjafjordur (O. D.)!. XW. Iceland: Hesteyri!. In both these places it was collected scantily only. Near Hof it occurred as a few scattered individuals in a specimen of the vegetation taken from wet boggy ground. Near Hesteyri it grew on very wet boggy ground. The plants were about 3 cm. high and sterile. Some of them agreed with var. anomalum; in some the leaves at the base of the stem resembled in structure those of the variety in having thin-walled cells 0.020—0.025 mm. in size, while the leaves in the upper part of the stem resembled in structure those of the type in having cells 0.015- 0.020 mm. in size. Var. anomalum is undoubtedly a hygrophilous form of P. gracile, which develops when the habitat is inundated. 203. Polytrichum sexangulare Floercke. Iceland (Morch)!. N. Iceland: Ljosavatn!; Reykjaheidi!; common near Eyjafjordur (O. D.;!). N\V. Iceland: Very common!. W. Iceland: Esja!; Kolvidarhol!. S. Iceland: Seljaland!; Holt!; Thingvallahraun !. Var. -vulcantcfi G. Jens. "Seta perbrevis usque ad 4 mm. longa; apophysis valde indistincta; capsula non angulata, vetusta nigrescens et irregulariter 4 — 5-gona; Cetero typo simile." S. Iceland: The volcano on the road to Holt (Stp.)!. Var. tenellum n. var. Plants 1—2 cm. high, more slender than the type, with shorter, narrower, more slightly incurved and not secund leaves, when dry; the nerve excurrent in a short mucro; otherwise exactl}r like the type. S. Iceland: Barkarstadr!; Drangshlid!; Seljaland!. Polytrichum sexangulare has a very peculiar distribution in Iceland. The type is a decidedly Alpine plant which does not feel quite at home until near the snow line, on the gravelly flats soaked by the melting snow. In N. Iceland it has been collected only at elevations of above 500 metres. In NW. Iceland, where the species is very common, it is met with everywhere from about 200—300 metres upwards. On northern slopes where the snow lies long it sometimes descends as far down as to the sea-level. Near Kolvidarhol it was common at about 400 metres, and on Esja everywhere at elevations of above 500 metres. P. sexangulare has not yet been collected in E. Iceland, but the reason can hardly be that it does not occur there, it must rather be due to the fact that the mountain heights were almost everywhere snow- covered at the time of the year (June, 1909) when there was an op- portunity of making collections there. This species has an area of dis- tribution not only on the mountain heights, but also in the lowlands. THE BRYOPHYTA OF ICELAND 503 a a a a b b b Fig. 10. Polijtrichnm sexangiilare Floercke var. tencUnni. a. in a damp, and b, in a dry condition (X 6). In lava clefts near Thingvellir and in deep lava clefts on Reykjarheidi (at an altitude of about 250 metres) it was found abundantly in several places in association with several other Alpine species, for instance Gymnomitrium concinnalum, G. varians, Pleuroclada albescens and Pohlia commutata. The occurrence of this species in such localities is un- doubtedly connected with the fact that there the conditions pertaining \ a be d Fig. 11. Polytrichum sc.i-cinfiiildre Floercke var. IcncUiun. a. b and c. leaves (X 15): (/. loaf-apex (X lOOj. 504 A. HESSE LBO to soil present certain points of resemblance to the mountain heights, as the snow in the deep clefts, the bottom of which is never reached by the rays of the sun, often remains till late into the summer. The occurrence of var. tenellum is more peculiar. It has been found only in S. Iceland, where it grew exclusively on dry or slightly damp blocks of tuff in the lowlands. But only near Seljaland did a few small tufts occur on a block of tuff at an altitude of about 600 metres. Near Drangshlid it grew abundantly on the fallen blocks of rock at the foot of the rock-wall behind the farm. There in company with Hijpnum cup ressi forme, Ceratodon, Didymodon nibellus , Rhacomitrium fasciculare and Brynm argenteiim it formed tufts of varying size on the top of the blocks in dry situations. Near Barkarstadr it was found on a some- what damp tuff- face, and creeping over fallen blocks of rock, in asso- ciation with Pohlia crada, P. grandiflora, Ancectangium compaction., JBry- oxiphium norvcgicum and Anthelia spp. The plants from these habitats were quite sterile, and exactly alike in all respects. The fruit, which is common in the Alpine form, ripens in August (Akureyri: ripe Aug. 13th; near Isafjordur: green in the first half of July). 204. Polytrichum piliferum Schreb. Polytrichiim pilosum Neck. Iceland (Morch)!. E.Iceland: Vallanes (H. J.;!). N. Iceland: Rey- kjahlid (Grl. ;!). NW. Iceland; Bildudalur (C. Hansen;!); Gnupr near D\ra- fjordur!; Armuli!; Arngerdareyri!. W. Iceland: Stykkisholmur (H. J. ;!); Grund in Skorradalur!; common near Reykjavik! ; Vide}7!; Hafnarfjordur (Wiinstedt) ! . S. Iceland: Krisuvik (Stp. ;)!; Drangshlid!. Occurs here and there, and is rather rare in the majority of the districts of Iceland. It grows on dry sandy ground, upon soil-covered rocks and on dikes, often singly among other mosses. It is absent from or rare in the most rainy parts of the country, for instance at the East coast and in South Iceland and is most frequent in those districts where the rainfall is least. Thus it occurs abundantly near M \vatn, where it is common in the lava-field. It is also rather widely distributed in •> NW. Iceland, here it is often found in abundance, for instance on sandy fields near Armuli and on rocks near Arngerdareyri. Fruit is common and ripens in the latter half of June. 205. Polytrichum juniperinum Willd. Commonly distributed. It grows on more or less dry ground, for instance on knolls in bogs, in the Rhacomitrium-canescens heath, on slopes among Hylocommm and Rhacomitrium etc., usually scattered among other mosses, more rarely in cohering tufts, and almost always sets fruit which ripens at the end of June and in the beginning of July (Seydisfjordur, July 6th; Isafjordur, June 24th). It is most widely distributed in the lowlands and does not appear to ascend much higher than about 400 metres above sea-level. THE BRYOPHYTA OF ICELAND 505 206. Polytrichum strictum Banks. E. Iceland: Hornafjordur. common!. N. Iceland: Husavik!; Akureyri, common to about 600 metres above sea-level!; Hof near Eviafiordur (O.D.)!; . . i • ' common from Geitaskard westwards to Hrutafjordur!. N\Y. Iceland: Common around Isafjordur!; Grunnavik!; Kaldalon!. W. Iceland: Grund in Skorradalur!; Olafsdalur (H. J.)!; Reykholtdalur, common! ; Reykjavik!. S. Iceland: Skalholt!, J1 ; Geysir (Stp.)!. Occurs rather commonly and often abundantly on wet boggy ground, but always sterile. In Reykholtdalur it also grows on warm ground. 207. Polytrichum commune L. Widely distributed on damp ground, both in bogs and along the banks of streams, but as a rule rather scantily. In the low land, where P. commune has its greatest distribution, the large coarse form is usually met with. In higher regions, where it is found up to a height of about 500 metres, it usually becomes slen- derer and lower in growth. Thus, near Akureyri, it occurred abundantly in a bog at an altitude of 500 metres as a low-growing, slender form, mixed with Hypmim stramineum. P. commune is one of the most frequent species near hot springs, where it grows sometimes mixed with Sphagnum and is then large and vigorous, sometimes in extensive mats interwoven with hepatics and is then usually low in growth with shorter leaves. On a warm substratum it often fruits freely, while it has or else been found in fruit only near Grunnavik in N\V. Iceland. Var. f€istigi«ttun (Lyl.) Wils. SW. Iceland: Svinahraun!, abundantly on damp soil at the edge of the lava-field. 208. Polytrichum Swartzii Hartman. NW. Iceland: Bseir!, sterile. Var. iiif/rescens (Warnst.) Hagen. S}rn. Polytrichum inconstcins Hagen. NW. Iceland: Thoroddstadaengjar (St.)!; Dynjandi!. The type grew on a damp slope in not-coherent tufts, about 15 cm. high: the plants were quite typical with sharply toothed leaves, and with lamellae, the marginal cells of which had the irregular form peculiar to P. Sivartzii. The variety grew on very wet or inundated ground in company with Hypnum stramineum, H. giganteum and Mnium cinclidioides similarly to P. gracile var. anomalum, and may be regarded as a form similar to the latter; as in aquatic forms of other species, both forms have flaccid-soft leaves with slightly developed stereom in the nerve and broader, slightly toothed leaf-margin; in the plant from Dynjandi the leaf-margin was almost entire. The Botany of Iceland. Vol. I. part 11. 33 506 A. HESSELBO FAM. BUXBAUMIACE.E. 209. Diphyscium sessile (Schmid.) Lindb. Webera sessilis Lindb. Common in East, South and West Iceland, and rather frequent in North-west Iceland, where it is common for instance in the district of Dyrafjordur. In North Iceland it has not been found east of Blondudalur. It grows on firm, bare ground, especially on the top of knolls or on small elevations of earth on slopes, where it forms low, dense cushions, dark brown in colour; it is common, at any rate in E. Iceland, as far upwards as 600—700 metres above sea-level. Fruit, which oc- curred only scantily in all places, was collected near Reykjavik, near Lundur in West Iceland and near Geitaskard in Blondudalur. FAM. FONTINALACE.E. 210. Fontinalis antipyretica L. Found in all parts of the country and common on stones in brooks and rivers, and sometimes also in stagnant water, up to about 300 — 400 metres above sea-level. Near Ljosavatn in N. Iceland it was found abundantly in a river even at an altitude of 300 — 400 metres, and near Isafjordur it occurred frequently as far upwards as 300 metres. It varies considerably in size, leaf-form and colour. In stagnant water (thus in very wet bogs near Jokulsfjordur) it becomes very robust, light brownish-yellow, with broad leaves. In swiftly flowing water there often occur slender, dark-green or brownish-green forms with strong metallic sheen, which agree most closely with var. montana H. Mtiller. In such forms the basal angles of the leaves are often somewhat concave, and formed of a single layer of cells, in which respects it comes very near to F. gracilis. This species is recorded Irom several localities by Gronlund, H. Jonsson and Feddersen, but all the specimens which have been investigated belong either to F. antipyretica or to F. androgyna. Only sterile specimens have been found. 211. Fontinalis islandica Cardot. E. Iceland: Faskrudsfjordur (Jardin, 1865) (specimens not inspected). 212. Fontinalis longifolia C. Jensen (Bot. Not. 1885, p. 83). "Gracilis, viridis et flavoviridis, elongata, mollis, rubricaulis, ramulis brevibus, patulis subremotis. Folia laxa, imbricata vel erecto-patentia mollia, carinata, annosiora, bifida, ovato-lanceolata, sensim longe acumi- nata, integra vel ad apicem lenissime serrulata, decurrentia, cellulis THE BRYOPHYTA OF ICELAND 507 ilexuoso-linearibus, apicalibus brevioribus, angulorum multo majoribus, rectangulis. Folia ramulorum angustiora. Flores et fructus ignoti.'' This species, which was first found by Feddersen in the Helga in S. Iceland, grew very abundantly on stones in the Reykirdalsa in SW. Iceland. This river has copious influx from the hot springs, so that, in the first days of June, the temperature of the water was about 12°, which was essentially higher than in the majority of the other rivers where the temperature was, as a rule, only about 4° -6°. Fig. 12. Fontinalis longi folia C.Jens. (Reykir: somewhat reduced). Fontinalis longi folia agrees most closely with F. hypnoides R. Hartm. The plant from the Reykirdalsa is rather robust, as much as 25 cm. long, very strongly and irregularly branched, with rhizoid-cushions around all the points whence the branches issue, and with plane or somewhat concave, longly tapering, very soft leaves, which only exceptionally are folded along the median line. The J plant is more slender than is the $ plant, with very numerous, narrowly ovate <^ flowers, which often occur in clusters of 2 — 4 on the main axis and branches and contain each 2—4 antheridia. The fruit, which in the beginning of June was developed to almost full size, but was as yet quite green, so that the peristome and spores could not be investigated, was found scantily on the lowermost part of the stem. As in F. hypnoides the capsule was half-exserted. 33* 508 A. HESSELBO 213. Fontinalis thulensis C. Jensen (Bot. Tids. 20, p. 110). "Laxe caespitosa, sat robusta, mollis, sordide luteola, inferne nigres- cens subnitida. Caulis usque ad 25 elm. longus, inferne plerumque nudus, plus minusque ramosus, ramis brevibus vel elongatis, erecto- patentibus, vel subsecundo-arcuatis, interdum acutis, cauli primario sat similibus. Folia dimorpha, tristicha; folia caulina erecto-patentia vel laxe imbricata, plus minusque distincta et recte carinata, interdum tantum complicata, late ovata-lanceolata, longe decurrentia integra vel apice in- distincte denticulata, adultiora subobtusa, juniora acuta, nunquam bi- fida, superiora vulgo 5—6 mm. longa et 2—3 mm. lata, inferiora minora, latere uno versus basim reflexo; folia ramulina minora et subangustiora, vulgo 3 — 4 mm. longa et 1,5 — 2 mm. lata, inferiora multo minora omnia ecarinata, valde concava, interdum complicata, erecto patentia, inferiora ramorum arcuatorum arete imbricata, superiora interdum subsecunda. Cellulae in media foliorum 0,007—0,013 mm. latae, 8—12 plo longiores. Alae basilares, planae, unistratae, e cellulis quadratis et hexagonis, aeque ac ceteris cellulis basilaribus, luteis formatae. Cetera ignota. Speciei americana F. Kindbergii valde affinis. sed ramis erecto-pa- tentibus, non pennatis, foliis eorum brevioribus et latioribus, cellulis angustioribus, colore luteolo (F. Kindbergii ferrugineus est) et nitore debiliore ." W. Iceland: The Laxa (Hjar&arholt), 21.7.1886 (Feddersen). Note. Fontinalis sqiiamosa L. is enumerated on older lists, but of the specimens from Iceland, contained in the collections, some belong to F. antipyretica, some to F. androgyna. 214. Fontinalis androgyna R. Ruthe. W. Iceland: The Ellidara near Reykjavik (Morch; Grl.; H.J.;!). In the Ellidara it grew abundantly in company with F. antipyretica on large stones and rocks under water. There not only ^ buds were found, but also a few ripe capsules on the lowermost part of the stem (5.8. 1909). FAM. 215. Leucodon sciuroides (L.) Schwgr. S. Iceland: Foss (H.J.)!; Drangshlid (H.J.;!); Stjornarsandur (H. J.)!; Hrutafell!. SE. Iceland: Hornafjordur!; Hof!. SW. Iceland: Hafnar- fjordur !. All the Iceland specimens belong to var. morensis (Schwagr.) de Not. It grows on dry rock-walls with a southern exposure, both on tuff and on basalt, and appears to be rather frequent from Hof in SE. Iceland throughout S. Iceland to Hafnarfjordur in SW. Iceland. It occurred abundantly on Hrutafell and Drangshlid, and covered the vertical faces of tuff-rocks for long distances. Here it was also richly fruiting with capsules which were partly ripe at the end of June. THE BRYOPHYTA OF ICELAND 509 216. Antitrichia curtipendula (Hedw.) Brid. E. Iceland: Hornafjordur, common!; Djupivogur!; Hof!; Starmyri!; Berufjordur!. N. Iceland: Modruvellir (Thoroddsen) ! ; Geitaskard!; com- mon in Vatnsdalur!. NW. Iceland: Patreksfjordur!; Kaldalon ! . Common in W. and SW. Iceland!. Common in SE. Iceland as far as Berufjordur (where it was found in one locality only), in S. and \V. Iceland and the western part of N. Iceland from Blondudalur. Rare and scanty in NW., X. and E. Iceland. It grows usually on a rather dry substratum, on stony slopes, and soil-covered rocks, but especially on moss-grown slopes in company with Hylocomiiim spp., and on the ground in coppices. In Esja it is common up to a height of 300—400 metres above sea-level. Only sterile specimens have been found. FAM. NECKERACE.E. 217. Neckera complanata (L.) Hub. W. Iceland: Gilsbakki!; Bardshellir (Grl.)L S.Iceland: Paradishellir (Stp.)!; Reykir!; Austarhlid near Geysir!; Breidabolstadr! ; Barkarstadr!; Holt!; Drangshlid!; Hrutafell!. Rare in W. Iceland, and rather common in S. Iceland. It grows everywhere on the roof and sides of dry caves, which it often covers with its extensive, dark-green mats. Only sterile specimens have been found. FAM. LESKEACE^E. 218. Myurella julacea (Will.) Br. eur. Very common on rocks, especially in humus-filled clefts ; occasion- ally also on the ground, for instance on knolls in bogs. It often occurs in unmixed cushions, but far more frequently mixed with other mosses, and is met with both on a dry and on a somewhat damp substratum. On wet rocks it often grows in association wit i Ancectangium Mougeottii. Philonotis, Blindia acuta, etc.; in dry clefts in company with Mnium or- thorrhijnchum, Plcigiothecium Roesei, Bartramia ityphylla, Pohlia criida, etc.; or it may be met with on dry rocks woven into the tufts of Hyp- mim revolutam and Grimmia spp. It does not appear to ascend higher than 300—400 metres. Only sterile specimens have been found. 219. Myurella tenerrima (Brid.) Lindb. Myurella apiculata Hiiben.) Br. eur. Grows quite similarly to the preceding species and, as a rule, in company with it. and in the majority of the districts of Iceland is almost as common. In S. Iceland it appears, however, to be somewhat 510 A. HESSELBO rarer. It is most frequent in rather damp situations, for instance on rocks near waterfalls. Only sterile specimens have been found. 220. Leskea nervosa (Schwagr.) Myrin. SE. Iceland: Hof!, on rocks in company with Metzgeria furcata, sterile. S. Iceland: Drangshlid!; Hrutafell!, sterile. In both the latter localities it occurred abundantly on drj7 tuff-faces or on large fallen blocks. 221. Leskea catenulata (Brid.) Mitten. Nupsdal (Stp.)!. Here, Gnupsdalur near Dyrafjordur in NW. Iceland is probably meant. 222. Anomodon viticulosus (L.) Hook, et Tayl. S.Iceland: Hrutafell!; cave near Skogafoss!. Vestmannaey!. On Vestmannaey it grew at the foot of a dry, stony slope below Stora Klit; near Hrutafell it grew sometimes on rocks, sometimes on soil-covered rock-ledges. Only sterile specimens have been found. 223. Pterigynandrum filiforme (Timm) Hedw. Very common everywhere. The most frequent form is var. decipiens (W. et M.) Limpr., which occurs abundantly everj^where on dry rocks, especially on perpendicular basalt- faces, where it often forms very large cushions 5—6 cm. deep. Here all transitional forms are also met with between the type and the variety. The type is developed in deeper shade and occurs especially in clefts and crevices, where it forms thin, adherent mats on the sur- faces of stones. Only sterile specimens have been found. Both forms are common up to about 300—400 metres above sea-level. 224. Lescuraea decipiens (Limpr.) Ptychodium decipiens Limpr. E. Iceland: Berufjordur !$, at an altitude of 80 metres. var. crassirete n. var. Leaf-cells very thick-walled, highly porous and distinctly papillose in the upper half of the leaf. Nerve very strong, 0.040—0.045 mm. broad for almost its entire length. NW. Iceland: Gnupsdalur, at an altitude of 280 metres!. L. decipiens is closely allied to L. saxicola and is often difficult to distinguish from the latter species. Peculiar to both are the narrow, highly thickened and porous leaf-cells, which in L. decipiens are more or less distinctly papillose with a papilla at each of the uppermost cell-angles, at the back towards the leaf-apex; while L. saxicola almost always has quite smooth leaves. In L. saxicola the upper half of the THE BRYOPHYTA OF ICELAND 511 leaf-margin is almost straight in outline, while in L. decipiens it is dis- tinctly concave, as in L. filamentosa. The variety grew abundantly on somewhat damp rocks; it is some- what coarser and less branched than the type which it resembles ex- actly in leaf-form and size of the cells. The leaf-cells in this form are so highly thickened and porous that the walls almost appear like a string of beads and are often broader than the cell-space. Fig. 13. a. Leaves of Lescurcea Breidlcri (X 20): b. leaves of L. radicosa (X 20); c. leaves of L. decipiens (X 20); d. leaves of L. decipiens v. crassirete (X 20): c, leaf- cells of L. decipiens (X 320): /. leaf-cells of /.. decipiens v. crassirete (X 320). 225. Lescuraea radicosa (Mitt.) Hagen. Lescurcea riyescens (\Vils.) Br. eur.; Pseudoleskea radicosa (Mitt.) Lindb. Ptychodium Pf undine ri Limpr. N. Iceland: Oxnadalur, Tvera!; sterile. In the above locality it grew scantily on a stone by the river. 226. Lescuraea filamentosa (Dicks.) Lindb. Psendoleskea atrovirens DicksJ Br. eur. Widely distributed. 512 A. HESSELBO Grows on stones and dry or somewhat damp rocks, and appears to be frequent, although not abundant, in all parts of the country up to about 300 metres above sea-level. In N\V. Iceland it is very common on stony slopes, and is often richly fruiting while it has or less been found sterile only. 227. Lescuraea Breidleri (Kindb.) Arn. et Jensen. Ptychodiiim oligocladum Limpr. E. Iceland: Berufjardarskard!, at an altitude of 600 metres; Seydis- fjordur!, 500 metres. N. Iceland: Reykjahlid!; Akureyri, at an altitude of about 770 metres!. Grimsey (O. D.}!; Oxnadalsheidi (Grl.) ! . NW. Ice- land: Dxrafjordur!; Gnupsdalur!; Isafjordur!; Sugandafjordur!; Grunna- vik!. S. Iceland: Barkarstadr!, at an altitude of 530 metres. Frequent on rocks and stones in the more highly situated parts of the country. It occurs in greatest abundance and in its most typical form on mountain heights at elevations of above 500—600 metres, where it is often the most abundant constituent of the vegetation. It has its main distribution in NW. Iceland, where, for instance around Isafjordur and Sugandafjordur, it occurs very abundantly on the rocky flats from about 200 metres upwards. D n c Fig. 15. Brachythecium longipilnm. a, Capsule (X20); /', branch-leaves (X20): c, stem-leaves (X 20). et tenuissimum recurvatum producta, per totam marginem denticulata^ 1—1.2 mm. longa, 0.4—0.6 mm. lata, costa brevi et indistincta. Folia ramorum erecto-patentia aut subsecunda, lanceolata, longius acuminata^ 1.4 — 1.6 mm. longa, 0.4—0.6 mm. lata, per totam marginem denticulata^ Fig. 16. Braclu/ Hied inn longipilnm. Leal-base (X175; phot.). costa mediam partem folii paulo excedente. Cellulae angusta?, sinuata3y 0.004 mm. latae, 0.060 — 0.075 mm. longae, basilares in uno vel duo se- riebus, ovales, porosse, pach}Tdermia3, 0.010 mm. latse, in angulis quadratse vel ovales, paucae. Perichretium e cauli primario egressum. Folia perichsetialia exteriora apice brevi, interiora apice longo reflexo, ecostata vel costa perbrevi et 520 A. HESSELBO indistincta, margine leniter dentato. Seta 8 mm. longa, c. 14 mm. crassa, purpurea, in dimidia parte superior! rugosa, inferne glabra. Capsula fusca, obliqua. longe ovata, operculata 1.7 mm. longa, 0.5 mm. crassa, deoperculata sub orificio contracta. Operculum conicum 0.6 mm. altum. Dentes peristomii 0.46 mm. longi, 0.067 mm. lati, pallide lutei, apicibus hyalinis, basi aurantiaci et leniter transverse striati. Sporse 0.021- 0.024 mm., papillulosae. S. Iceland: Flokastadagil, on stones at the margin of the river. The capsules were empty in the middle of July. 249. Brachythecium populeum (Hedw.) Br. eur. Hypnum populeum Hedw. S. Iceland: Vik (H. J.)!, fr.; Drangshlid!, fr. Grew in both the above localities on rather dry tuff rocks. 250. Brachythecium velutinum (L.), Br. eur. S. Iceland: Thingvellir (Grl.;!); Vik (H.J.)!; Holt!, in a cave at an altitude of about 300 metres, fr. Near Thingvellir it grew in a lava-cleft, associated with Blepharo- stoma trichophyllum, Plagiochila asplenioides and Plagiothecium silvaticum. 251. Brachythecium glaciale Br. eur. Hypnum glaciale C. Hartm. N.Iceland: Akureyri!, at an altitude of 770 metres. NW. Iceland: Sugandafjordur!, at an altitude of 450 metres. W. Iceland: Dalasysla, Melar, on a cliff inhabited by sea-fowl (H.J.)!. On damp gravelly flats. Near Sugandafjordur it grew abundantly, intermixed with Hypnum straminenm, Mniobryum albicans and Philonotis fontana, in cushions 3—4 cm. deep, on ground saturated by melting snow, and on stones. The plants were about 5 cm. long and irregularly branched with unequally long mostly short branches. The leaves were erectly spreading, not secund, and very longly decurrent with numerous quadrate, thin-walled cells at the basal angles of the leaves. 252. Brachythecium reflexum (Starcke) Br. eur. Commonly distributed. This species has its main distribution in gravelly spots on the rocky flat, especially on slopes and dry snowless patches on the moun- tain heights. It is especially abundant in NW. Iceland, where it is everywhere the most frequently occurring species on stony slopes. Here it is usually found associated with Hypnum uncinatum, Lescurcea spp., Lophozia lycopodioides, L. Flcrrckei, etc., and is met with as high as about 500 metres above sea-level. In Esja, in SW. Iceland, it was common from about 200 metres upwards. In the low land it is rarer and appears THE BRYOPHYTA OF ICELAND 521 to occur more particularly in the lava-fields, for instance near Hafnar- fjordur. Thingvallahraun and Kihlhraun. It is found rather frequently in fruit. 253. Brachythecium glareosum (Bruch) Br. eur. Hypnuni glareosum Bruch. E. Iceland: Seydisfjordur, on stones!. X. Iceland: Tvera in Oxna- dalur, on damp gravelhT ground!. W. Iceland: Botnsdalur. on damp rocks!. 254. Brachythecium albicans (Neck.) Br. eur. Hypnum albicans Neck. Commonly distributed over the whole of Iceland. V This species grows on a dry substratum, for instance on sandy or grass-covered ground, on soil-covered stones, on dikes and on the peat- walls of houses. It is most frequent in the low land up to a height of about 300 metres, but occasionally, for instance near Akureyri, it ascends as high as about 600 metres above sea-level. Only sterile speci- mens have been found. 255. Brachythecium erythrorrhizon Br. eur. Hypnum erythrorrhizon Hartm. N. Iceland: Hof near Eyjafjordur (O. D.)!; Ljosavatn!; Tvera in Oxnadalur!. W. Iceland: Esja!. Found in all the localities only scantily intermixed in the tufts of other mosses on rather dry ground. Near Ljosavatn it grew in the Betnla nana heath in association with Hylocomium proliferum, Hypnum uncinatum, Heterocladium squarrosiiliim and Lophoiia hjcopodioidcs : in Esja it grew on a slope with a southern exposure, in company with Hylocomium spp. and Hypnum imponens. 256. Brachythecium rivulare (Bruch) Br. eur. Hypnum rivulare Bruch. Very common over the whole of Iceland. One of the most frequent mosses, which occurs everywhere on damp ground up to about 400—500 metres above sea-level. It occurs both in large and small streams, where it covers the stones or the gravell}7 soil along the banks with its extensive mats, and in bogs, and is also one of the species which is most frequently met with in moss bogs. Occasionally, however, it grows also on a more dry substratum, for instance on soil-covered rocks and among grass. Only sterile speci- mens have been found. The Botany of Iceland. Vol. I, part II. «*4 522 A. HESSELBO 257. Brachythecium latifolium (Lindb.) Philib. Hypnnm latifolium Lindb. Gja near Alptagerdi (St.)!, in company with Mnium pnnctatnm. 258. Scleropodium purum (L.) Limpr. Hypnnm purum L. SW. Iceland: Alafoss!. S. Iceland: Breidabolstadr!; Barkardstadr!; Holt!; Drangshlid!; Skogafoss!. This species has been found only in the southern part of Iceland, where it is frequent on Fljotshlid and below Eyjafjall. Near Alafoss it grew on the slope stretching down towards the river in which the temperature of the water was about 25°. Usually it grows at the foot of cliffs with a southern exposure, or in clefts, and, as a rule, in asso- ciation with Hylocomium spp., Eurhynchium pilifemm, Mnium undulatnm, Thuidinm delicatulum and- T. tamariscinnm. -*f - 259. Eurhynchium strigosum (Hoffm.) Br. eur. Hypn n m s trigosn m Ho ff m . Var. prwcox (Hedw.) Lindb. N.Iceland: Hof (O. D.)!; Vidimyri (Grl.)!. W Iceland: Kalmanstunga Grl.)!; Gilsbakki!; Reykjavik!. S. Iceland: Barkarstadr!. Grows everywhere rather scantily on dry soil-covered rocks or on tuff. 260. Eurhynchium diversifolium (Schleich.) Br. eur. Hypnnm strigosum var. diversifolium Lindb. N. Iceland: Reykjahlid!; Hofsfjall near Eyjafjordur (O. D.)!; Akureyri, at an altitude of about 900 metres!. Near Akureyri it grew in gravelly soil at the summit of the moun- tain, interspersed in tufts of Sphcerocephalus tiiryidus, Dicrannm congestnm and Hylocomium proliferum. Near Reykjahlid it grew intermixed in a tuft of Timmia anstriaca. Eurhynchium prcecox and E. diversifolium are so closely allied that, according to my opinion, it is doubtful whether the last species can be regarded as anything more than a decidedly Alpine form of Eurhynchium strigosum. The leaves in the plants determined as E. diversifolium are longly decurrent. The cells of the basal angles of the leaves vary considerably in number, even on the same plant, usually they are very numerous; but specimens of E. strigosum var. prcecox from Central Europe also vary considerably in this respect, and often have many more alar cells than has the type. THE BRYOPHYTA OF ICELAND 523 261. Eurhynchium cirrosum (Schwagr.) Limpr. Brachijthecinm cirrosum (Schwagr.) Schimp. SW. Iceland: Esja!; Kolvidarhol !, at an altitude of about 300 metres. In Esja it grew rather scantih7 on a damp slope, in company with Hypnum chrysophyllum. Near Kolvidarhol it grew abundantly on the ground among grass and species of Carex. 262. Eurhynchium piliferum (Schreb.) Br. eur. Hypnum piliferum Schreb. W. Iceland: Budahraun (H. J.)!; Alafoss near Reykjavik!; Hafnar- fjordur!. SE. Iceland: Hornafjordur!. S. Iceland: Reykirdalur !, up to about 150 metres above sea-level; Breidabolstadr!; Holt!, in several places up to about 300 metres above sea-level; between Thingvellir and Geysir (Grl.)!; common around Thingvellir!; Drangshlid!; Vestmannaey !. Rather common in the South-western and Southern parts of Iceland. It usually grows in protected localities, for instance in lava-clefts, but occasionally, for instance near Reykir, it occurs on moss-grown slopes in company with Hylocominm spp. Near Thingvellir it was found abun- dantly in Almannagja, at the grass-covered bottom of the ravine. Only sterile specimens have been found. 263. Eurhynchium Swartzii (Turn.) Curnow. / Hypnum Swartzii Turn. S. Iceland: Drangshlid (H. J.:!); Merkjafoss (F.)!; common on Fljots- hlid and below Eyjafjall!; Reykirfoss!. SW. Iceland: Alafoss. This species was found only in S. Iceland, but was common there on damp rocks, especially at the base of the sides of tuff rocks in clefts and in damp caves. Only sterile specimens have been found. Note. Eurhynchium hians from Merkjafoss Jeg Feddersen) belongs to E. Swartzii. Hypnum prcelongum is recorded from Iceland by Zoega. There are no specimens of it in the collections, but perhaps it has been con- fused with E. Swartzii 264. Eurhynchium Stockesii (Turn.) Br. eur. Hypnum Stockesii Turn. S. Iceland: Drangshlid!; Hrutafell!; Holt!; Seljaland!; Vestmannaey (H. J.;!). Rather common south of Eyjatjall and on Vestmannaey. It usually grows rather scantily on the ground, between blocks of rock or in clefts. On Vestmannaey it occurred in several places; among other localities at the foot of cliffs, in company with Mnium undiilatiun and Lophocolea cuspidata. Only sterile specimens have been found. 34* 524 A. HESSELBO 265. Rhynchostegium murale (Neck.) Br. eur. Hypnnm murale Neck. S. Iceland: Drangshlid!; Hrutafell!. In the above localities it grew rather abundantly at the foot of dry tuff rocks and on fallen blocks. The fruit was ripe in the latter half of July, but some of the lids still persisted. 266. Rhynchostegium rusciforme (Neck.) Br. eur. Hypnnm rusciforme Neck. N. Iceland: Near Eyjafjordur (O. D.)!. NW. Iceland: Isafjordur!. W. Iceland: Dalsmynne in Nordredalur!; Lundurreykjadalur! ; Esja!; Ellidara near Reykjavik!. S. Iceland: Tungufoss F.)!; Vik (H. J.)!; Reykirdalur!, fr. ; frequent on Fljotshlid and near Eyjafjall!. Var. atlanticnm Brid. N. Iceland: Between Svinadalur and Dettifoss!; Husavik!. W. Iceland: Esja!, in several places. S. Iceland: Reykirdalur!; Holt!; Vik (H. J.)!. The type is rather frequent in the Southern and Western parts of Iceland, rarer in North Iceland, and has not been found in East Iceland. It usually grows on wet rocks near waterfalls, or on stones in the rivers, as a rule rather scantilj7, and mixed with Brachythecium riuulare, Hypnnm ochraceum, etc. Only in Reykirdalur did it occur abundantly in the river and on the rock-sides by the waterfall, also in fruit. Var. allanticiim is found in swiftly flowing rivers, where it often covers the bottom and stones for long distances. 267. Thamnium alopecurum (L.) Brid. W. Iceland : DalasVsla, Vogur H.J.)!; Jserngerdarstadr (Ssemundson)!. S. Iceland: Reykirdalur!; Paradishellir (Stp.)!; common on Fljothlid and below Eyjafjall!. On wet shady rock-faces and in caves. In S. Iceland it is common in the tuff-clefts, especially on the inwardly sloping surfaces, and in the numerous dark, damp caves, where it often covers the roof and sides through which water is percolating. Only sterile specimens have been found. 268. Plagiothecium silvaticum (Huds.) Br. eur. N. Iceland: Grimsey (O. D.)!. S. Iceland: Thingvellir (Grl.;!); Al- mannagja !. In Almannagja it was found scantily at the bottom of a lava-cleft. Onry sterile specimens were found. 2(>9. Plagiothecium Roeseanum (Hampe) Br. eur. Syn. Plagiothecium silvaticum var. Roesei (Hampe) Lindb. Commonly distributed, but as a rule rather scantily, in soil-filled rock -ere vices, in company with Mnium orthorrhynchiim, Plagiochila 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. 526 A. HESSELBO The form found is robust, light green, highly shining and differs in habit by the leaves being very decidedly two-rowed, spreading. Gemmae, which were, by the by, quite typical, occurred only extremely few in number. 274. Amblystegium Sprucei (Bruch) Br. eur. Commonly distributed over the whole of Iceland. Grows in rock-clefts, dark ravines and caves, and among fallen blocks of rock, usually scantily woven into the tufts of other mosses such as Plagiothecium pulchellum, Amphidium Mougeottii, Lophozia MtiUeri. L. heterocolpos and Mniiim orthorrhynchum, but occasionally also in tiny cushions or as delicate, cobweb-like coverings on roofs in caves. In Esja it was found up to about 400 metres above sea-level. Only sterile specimens have been found. 275. Amblystegium fluviatile (Sw.) Br. eur. SW. Iceland: Tungufoss (F.)!, determined by C.Jensen. Only a few stems were found, intermixed with other mosses, for instance Brachytheciam riuiilare, Hypnnm ochmceiim, etc. 276. Amblystegium serpens (L.) Br. eur. N. Iceland: Akureyri, fr. (Grl.)!; My vat n, fr. (Grl.)!. \V. Iceland: Reykjavik!. Vestmannaey !, fr. In Iceland this species is as variable as it is in other places. The specimens from Mwatn were very robust, with leaves 1.33 mm. long and 0.65 mm. broad, erectly spreading, and distinctly toothed in their lower half, with rather long and strong nerve, and cells 0.010 — 0.012 mm. broad and 4—6 times as long. Near Reykjavik it grew in large cushions, 1 — 2 cm. deep, on a stone wall near the sea-side. In the plant from the latter locality the leaves were broadly ovate, longly pointed and almost entire at the margin, with cells 0.009—0.011 mm. broad and 2—3 times as long. The form from Yestmannaey is very slender, with leaves 0.7 mm. long and 0.3 mm. broad, with very short nerve which in the branch leaves was just indicated immediately above the leaf-base. On Vestmannaey the fruit was quite unripe on July 6th; in N. Iceland it was ripe at the end of July. 277. *Subsp. Amblystegium Juratzkanum Sdiimp. .N.Iceland: Fagriskogur (St.)!. S. Iceland: Drangslilid !, fr.; Vest- mannaey!. The plant from Drangshlid was quite typical and bore ripe capsules at the end of July. The specimens which were collected on the base of a birch-trunk in Fagriskogur agreed fairly well with the form described by Limpricht (Kryptogamentlora, vol. Ill, p. 323) under the name of Amblystegium radicale. The leaves taper from an ovate-lanceolate base 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 6—8 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- A. HESSELBO 0.006 mm. broad, and 6—10 times as long, thin-walled, pointed and wavy. On the whole, both the cell-tissue of the leaf and the form of the leaf-teeth call to mind far more an Eiirhijnchium or a Rhynchosteginm than an Amblystegiam. Amblystegiu.ni salinum Bryhn grows in loose, yellowish green, hardly tomentose tufts. Rhizoids occur only on the lowermost part of the stem and scantily on the back of the nerve. The stems are erect or ascending, slightly and irregularly branched. The leaves are far more distant than in A. compactiim, are spread out almost horizontally, very longly decurrent, ovate-lanceolate, with long, often somewhat obtuse apex; all are similar or the branch leaves are somewhat narrower. The leaf- margin is finely and obtusely toothed till towards the apex. The leaf- cells have the appearance typical of Amblystegium, and in the upper half of the leaf are 0.008 mm. broad and 4—6 times as long, with sinuose primordial utricle (the latter is usually wanting in A. compactiim} f The nerve is green and sinuose (as in A. variuni) and vanishes just below, or in, the leaf-apex itself. A. salinum is undoubtedly a true Eii- Amblystegiiim which is nearest allied to A. serpens, but also approaches certain forms of A. varium (Hedw.) as regards the form of the basal cells of the leaf and the long sinuous nerve. It would also be remark- able if a species like A. compactiim, which in North America grows on rocks and on damp ground in woods in the interior of the country, should in Europe turn into a decidedly salt-soil plant. A. salinum has been collected in many places along the coasts of Sweden and Norway; first by Zetterstedt on Oland and near Bosekop in Finmarken, and in the herbarium is named by him Amblystegium serpens var. litlorale. Ha gen has collected Ihe same species in Salten in Nordland (65° 15' N. lat.), where it was growing in company with A. littorale (C. J.), and in a letter he named it Amblyslegium breve n. sp. On the other hand, it is not known to me that the real A. compactiim has been collected in Scandinavia. I have not seen the A. compactiim from salty soil in North Germany mentioned by Loeske (loc. cit. pp. 272— 273), nor have I seen Monkemeyer's A. compactiim from Bornholm. 280. Amblystegium salinum Bryhn. Vestmannaey! on damp sandy soil near the coast, sterile. 281. Amblystegium trichopodium (Schultz) Br. eur. N. Iceland: Grimsey (O. D.)!. Judging from the plentiful intermixture of Green Algae, the plants from the above localitj' must have been growing on wet, probably muddy ground. ^ and $ flowers were present in great numbers; fruit, on the other hand, had not been developed. The stem leaves were rather close- set, horizontally out-spreading, from an ovate base tapering to a long and slender point, finely toothed along the entire margin, 1.2 — 1.5 mm. long and 0.50—0.55 mm. broad, with green nerve, 0.04—0.045 mm. wide. The branch leaves were lanceolate, 0.95 mm. long and 0.30—0.35 mm. broad, with short green nerve. At the base of the leaf the cells were THE BRYOPHYTA OF ICELAND 529 green and rectangular, 0.018 mm. broad and 0.070 mm. long, in its upper half, 0.010 mm. broad and 4—7 times as long, with sinuous primordial utricle. Fig. 17. AmMysteginm trichopodinw (Schult/). Habit (X 3). a Fig. 18. Ambhjsteginm trichopodinm (Schultz) Br. our. a. Stem-leaves and b, branch-leaves (X20); c, leaf-cells near margin (X120). 530 A. HESSELBO 282. Hypnum Sommerfeltii Myrin. N.Iceland: Stora Brekka near Eyjafjordur (O. D.)!. S.Iceland: Fell (Harder, 1908)!, a few stems " among Hypnum iincinatum, H. stellatum and Diirichum fle.vicaule. 283. Hypnum chrysophyllum Brid. Amblystegium chrysophyllum (Brid.) Lindb. E. Iceland: Berufjordur!. N. Iceland: Near Myvatn vGrl.)!; Hof near Eyjafjordur (O. D.)!. W. Iceland: Esja, several places (Grl.;!). S. Iceland: Geysir, on warm ground!. Vestmannaey, Heljusdalur!. Var. $ tettellum Schimp. W. Iceland: Esja!. On damp gravelly ground and on rocks, rather rare and scanty. Near Geysir it grew plentifully on warm damp ground ove% which the tepid water from the basin was flowing. Only sterile specimens have been found. Hypnum Zemlice C.Jensen, which was collected by Steenstrup (but no habitat is given) is only a form of Hypnum chrysophyllum. 284. Hypnum protensum Brid. Amblystegium protensum Lindb. E. Iceland: Skrciddalur!; Seydisfjordur!. N. Iceland: Hof (O. D.)!: frequent in Esja!. This species is probably widely distributed, but, on account of its great resemblance to the far more commonly occurring H. stellatum, cannot always be kept distinct from the latter species. It grows in somewhat damp localities, both on stones and on the ground, but only sterile specimens have been found. 285. Hypnum stellatum Schreb. Amblystegium stellatum (Schreb.) Lindb. Very common everywhere on a damp substratum, on rocks, on the ground and in bogs, and not rarely in fruit. It is abundant even at a height of 500—600 metres above sea-level. 286. Hypnum polygamum (Br. eur.) Wils. Amblystegium polygamum Br. eur. Very common on wet, boggy ground. It occurs especially abundantly in the neighbourhood of the coasts, but is also very common in the valleys further inland, and hardly ascends higher than about 300 metres. Fruit, which is met with very frequently, ripens at the end of June or in the beginning of July. THE HRYOPHYTA OF ICELAND 531 287. Hypnum intermedium Lindh. Amblystegium intermedium Lindb. This species is no doubt common, at least in X. Iceland, where it occurs around Eyjafjordur up to about 500—600 metres above sea-level. Only sterile specimens have been found. 288. Hypnum revolvens Sw. Amblystegium revolvens De Not. Very common over the whole of Iceland. One of the most frequent and abundantly occurring mosses, which often forms the bulk of the vegetation in the bogs, both in the low land and in the Alpine region where it is plentiful even at an altitude of about 600 metres, for instance near Eyjafjordur. Fruit, which is often present abundantly, ripens in the beginning of July. Hypnum revolvens is distinguished from H. intermedium only by the fact of its being monoicous. Therefore, in cases of the frequently occurring quite sterile plants, it is really impossible to decide whether they belong to the one or to the other species. This is especially true of the vigorous, slightly branched aquatic forms, which had previously been referred to Hypnum Cossoni Schimp. Both H. revolvens and H. intermedium form such Cossoni- forms, but as they are mostly quite sterile it is impossible to determine them with any certainty. 289. Hypnum uncinatum Hed\v. Amblystegium (iduncum (L.) Lindb. Very common everywhere upwards to the limit of plant-growth. Var. orthothetioides (Lindb.). X. Iceland: Grimsey (O. D. !. XW. Iceland: Arngardareyri !: Grun- navik!. E.Iceland: Kirkjubol (H. J. .'. Hypnum uncinatum is one of the most common mosses and occurs everywhere both on dry and on damp substrata, on earth, on rocks, in bogs, etc.; and often in such quantities that it is the most abundant constituent of the moss-carpet. It varies exceedingly in size, habit and colour. Hypnum orthothecioides cannot be maintained as species; in addition to the forms found in the above-mentioned habitats, others forming all possible transitions to the type have been found in many other localities. Fruit, which is rather common, ripens in the first half of July. 290. Hypnum Sendtneri Schimp. Amblystegium Sendtneri Schimp. De Xot. N. Iceland: Helgavatnsfloi (Stp.)!. 532 A. HESSELBO 291. Hypnum Kneiffii (Br. eur.) Schimp. Amblgstegium Kneiffii Br. eur. This species is common, especially in N. and E. Iceland, and is somewhat rarer in NW. and S. Iceland. It grows in very wet situations in bogs, in pools, along the banks of rivers or covering stones in the water. Aquatic forms with slightly secund, longly pointed leaves are fre- quent; short and broad leaved orthophyllous or drepanophyllous forms occur more rarely. The size of the leaf-cells is dependent on the form of the leaf; in f. brevifolia they are short in the middle of the leaf, about 3 — 4 times as long as they are broad. In Esja a brevi-orthophyllous form was collected in a moss-bog at an altitude of 410 metres. It has been collected in fruit only near Husavik in N. Iceland. 292. Hypnum exannulatum (Giimb.) Br. eur. Amblystegium exannulatum De Not. Very common. Hypnum exannulatum occurs in numerous forms everywhere on a damp substratum, often forming the bulk of the vegetation, either alone or mixed with other Hypnacecc (H. stramineum, H. revolvens, etc.), with Cinclidium, Mnium spp., and other bog mosses. It grows not only in bogs, but also in pools, moss-bogs, along streams, and occasionally on damp rocks. Near Akureyri it was abundant even at an altitude of 600 metres. Var. purpuntxcens (Schimp.) (Hypnum purpurascens Limpr.) is the most frequent form, at any rate in N. and E. Iceland. It is usually purplish, more rarely green, erect, as much as about 20 cm. high, and often forms large, pure growths on very wet ground, especially in the water itself, for instance along the banks of small streams. In this form the leaf -base is never decurrent. In the plants which have been in- vestigated the cells of the leaf- base are sometimes quite typical, forming a single row of large dilated cells across the entire leaf-base, and some- times they approach those of the type by forming a more or le^s large, triangular group of empty cells towards the leaf- margin. In typical Hypnum exannulatum the leaves are alwaj's narro\vly decurrent. Var. Rotcv (De Not.) is without doubt an extreme aquatic form of var. purpurascens, with which it is closely connected by intermediate forms. It has the solid, tough stem with long, forwardly directed branches and very narrow, slightly secund leaves peculiar to all mosses growing in swiftty flowing water. The nerve is very strong, usually 0.10 mm. wide at the base and, as a rule, vanishing in the apex, more rarely excurrent. It grows in running water, often in streams (lowing through boggy ground. Typical specimens were collected in the following localities: E. Iceland: Seydisfjordur !, rather common; Breiddalskard!; Frodarheidi (H J.)!. NW. Iceland: Kaldalon!; DVnjandi!. W. Iceland: Hvammur (Grl.)!; Esja!, at an altitude of 100 metres. Only sterile specimens have been found. THE BRYOPHY1 A OF ICELAND 533 Var. serrftfus (Warnst.). Isafjordur!, in pools. In H. exannulatum the length of the leaf-cells varies according to the shape of the leaf. In the most commonly occurring forms with longly pointed leaves the cells are narrow, 6—10 times as long as broad, while short-leaved forms have leaf-cells which are only 4—6 times as long as broad var. brachydictyon (Ren.), such forms are especially met with on cold, wet gravelly ground. Fruit is rather frequent, both in the type and in var. purpiirascens, and ripens at the end of July. 293. Hypnum fluitans (Dill.) L. Amblystegium fluitans (L.) De Not. S. Iceland: Breidabolstadr (F.)!; Breidamerkursandur (Harder!. N. Iceland: Blejkjuholt (St.)!; Myvatn Grl.)!. Monoicous forms, which may be referred to H. fluitans occur only very scantily and rarely in Iceland. The numerous older records of the occurrence of this species ,'Yahl, Morch, Hornemann, Gronlund, etc. are, without exception, due to erroneous determinations, and all the older specimens in the collections (except one) belong to H. exannu- latum or H. Kneiffii. H. fluitans grows everywhere in pools or on inundated ground. Near Blejkjuholt • Stefansson has collected a very peculiar form, with erect, obtuse leaves with short nerve. The cell-tissue of the leaves is very loose, and the cells of the leaf-base differ only slightly from the other cells. \7ar. falcatum Schimp. (Hypnum H. Schultzii Limpr.) This very characteristic form was found abundantly, and in fruit, on wet boggy ground near Kaldalon in NW. Iceland. 294. Hypnum filicinum L. Amblystegium filicinum (L.) De Not. Very common. In the greater part of Iceland this species is one of the most fre- quent mosses on a damp substratum, especially on wet rocks, but also on gravelly ground and in bogs. In most part of N. Iceland it is some- what rarer, and usually occurs more scantily. In S. Iceland it often covers the faces of wet tuff-rocks in enormous mats and not rarely sets a great quantity of fruit. In the rest of Iceland fruit is rarer and occurs most often in the large, tomentose bog-form. In S. Iceland fruit was ripe in the middle of July. Hypnum filicinum varies exceedingly. Bog forms and forms from wet gravellj7 ground are usually densely tomentose and regularly pinnately branched. Rock forms, when growing on a more dry substratum, are slender and slightly branched: on wet rocks, especially on tuff, very large and vigorous, often almost like Hypnum commutatum. 534 A. HESSKLBO H. filiciiium has its main distribution in the lowlands up to about 300 metres above sea-level, but is also frequently met with, for instance near Berufjordur and in Esja, up to a height af about 500 metres. At this altitude it grows on rocks in low, dense cushions, more rarely on wet gravelly ground, and these Alpine forms constitute a distinct transition to H. curvicaule Jur., which is perhaps only a High Alpine form of H. filicinnm. 295. Hypnum curvicaule Jur. Amblystegium curvicaule (Jur.) Dicks. & James. E. Iceland: Berufjardarskard !, 540 metres above sea-level; Seydis- tjordur!, frequent from about 100—500 metres above sea-level. \V. Iceland: Modruvellir !, about 400 metres above sea-level. Grows on damp gravelly ground and rocks on mountain heights up to 500—600 metres. On dry rocks the leaf-cells become longer and narrower and the alar cells more thick-walled. Near Seydisfjordur it was collected with quite young fruit 3. 7. 1909). 29(5. Hypnum decipiens (De Not.) Limpr. Amblystegium glanciim {j. decipiens Lindb. E.Iceland: Very common near Seydisfjordur!; Dvergasteinn (H. J. ! N. Iceland: Husavik!; Ljosavatn!; Akureyri!; Oxnadalur!. W. Iceland Brattabrekka!. Common from Seydisfjordur in E. Iceland throughout the whole of N. Iceland. The westernmost habitat of this species is Brattabrekka, south of Haukadalur. In the rest of Iceland it has not been observed. Hypnum decipiens grows on very wet, especially gravelly, ground, for instance at the edge of moss-bogs or on inundated gravelly ground, and along small streams both on the ground and on stones. It hardly ascends higher than about 300 metres, and rarely sets fruit. Near Seydisfjordur, Husavik and Tvera in Oxnadalur it was collected in fruit. 297. Hypnum commutatum Hedw. Amblystegium glauciim (Lam.) Lindb. E. Iceland: Seydisfjordur (H. J.;!). N. Iceland: Husavik!; Reykjahlid !. \V. Iceland: Lundur!; rather frequent in Esja!. S, Iceland: Rather common !. Var. falcatum Brid.) C. M. Hypnum falcatum Brio1. Very common. H. commutatum is the more rarely occurring form. It is most frequent in SW. and S. Iceland, where it is especially abundant on wet tuff-rocks. It is rather rare and scanty everywhere else in Iceland. Var. falcatum, together with all possible transitions to the type, is one of the most common mosses in the greater part of Iceland. Only in N\V. Iceland is it scanty and met with only here and there. Both THE BRYOPHYTA OF ICELAND forms grow on rocks in and by the water, on wet rock-faces and on the ground, both on wet gravelly ground and on the ground in bogs. It often forms, especially in N. Iceland, an essential part of the moss- carpet in bogs. It hardly ascends higher than about 300 metres above sea-level. $ plants are very common, ^ plants and fruit are far rarer. It has been found in fruit near Stafafell, Seydisfjordur, Hrutafjordur and, rather frequently, in S. Iceland (both forms . 298. Hypnum molluscum Hedw. Ctenidium molluscum (Hedw.) Schimp. Iceland (Morch)!; Bardshellir (Grl.)!; Brynjudalur Grl.)!. W. Iceland: Common near the hot springs in Reykholtdalur!; Botnsdalur!; common about Reykjavik!; common in Esja!; Kolvidarhol! , up to about 350 metres above sea-level. S. Iceland: Very common!. SE. Iceland: Horna- fjordur!. This species is very common in S. Iceland, especially on Fljotshlid and about Eyjafjall, but is also plentiful near Thingvellir, and frequent in SW. Iceland as far as Borgarfjordur, where it is, however, chiefly confined to the warm ground. It appears to be quite absent from the other parts of Iceland. H. molluscum grows on a damp substratum, both on damp rocks, especially tuff, and on damp ground. Near Thingvellir it grew abundantly, covering the blocks at the bottom of the large lava-clefts. Around the hot springs in SW. and W. Iceland it occurs abundantly in several places. Thus in Reykholtdalur it is one of the most frequent species of the warm clayej7 flats. It occurs almost exclusively in the low land, and onlv near Kolvi- «, ^ darhol was it found about 350 metres above sea-level. Only sterile specimens have been found. 299. Hypnum imponens Hedw. Stereodou imponens (Hedw.; Brid. E. Iceland: Hof, on basalt rocks!. \V. Iceland: Esja!; Braudarholt !. N. Iceland: Vidimyri, near a hot spring (Grl.)!. W. and SW. Iceland : Near almost all the hot springs!. In SW. and W. Iceland it grew with a few exceptions on warm ground. In Esja it grew in company with Camptothecium lutesccns on a grass-covered slope, and near Braudarholt intermixed with other Hynacece on the top of knolls in bogs. On a warm substratum Hypnum imponens grows especially on the drier clay-flats; there it often forms extensive mats, partly alone, partly mixed with Hypnum stramineam, H. Lindbergii, H. molluscum, Hijlocomium squarrosum and other species. Only sterile specimens have been found. 536 A. HESSELBO 300. Hypnum Bambergeri Schimp. Stereodon Bambergeri (Schimp.) Lindb. W. Iceland: Breidabolstadr in Reykholtdalur!. It was growing there on a damp gravelly flat in company with Ditrichnm flexicaule, Myurella julacea, Tortella tortuosa and T. fragilis. 301. Hypnum revolutum (Mitt.) Lindb. Stereodon revolutus Mitten. Very common over the whole of Iceland. It grows both on dr}r and on more or less damp rocks, occasionally also on gravelly soil, and is frequent up to about 600—700 metres above sea-level. It varies considerably in size, from quite slender forms (for instance on lava blocks) to very robust forms on damp stones in clefts. Fruit, which was ripe in the middle of July (but the lids still persisted), was found only near Breidabolstadr in S. Iceland, where Hypnum revo- lutum grew in deep cushions, covering stones in a cleft. 302. Hypnum cupressiforme L. E. Iceland: Berufjordur (Grl.;!); Hof!; Hornafjordur!. N. Iceland: Vidvik near Skagafjordur (P. Sofoniasson)!; Vidimyri!; common west of Blondudalur!. W.Iceland: Stykkisholmur! ; Botnsdalur!; common about Esja, Hvalfjordur. Reykjavik and Hafnarfjordur!. S. Iceland: Common!. Vestmannaey!. Common from Berufjordur in E. Iceland throughout S. and W. Iceland and the western part of N. Iceland to Blondudalur. In E. Iceland it has not been found further northwards than Berufjordur, and in NW. Iceland it has not yet been observed. East of Hunafloi it has been found only in a few localities near Skagafjordur. It usually groxvs on rather dry rocks or on soil-covered rock-ledges, and does not appear to ascend higher than about 300 metres above sea-level. Only sterile specimens have been found. Var. ericetoruiN is recorded from Ormarstadir in E. Iceland (leg. H. J., det. C. Jensen), but there are no specimens of it in the collections. 303. Hypnum hamulosum Br. eur. Stereodon hamulosiis Lindb. E. Iceland: Hof!, at an altitude of 100 metres; Hornafjordur!. W. Iceland: Esja, Modruvellir!, on tuft' rocks, 250—400 metres above sea-level; Kolvidarhol ! ; common on tuft', from 250 to 450 metres. NW. Iceland: Grun.navik!, at an altitude of about 280 metres. S. Iceland: Holt!; Drangshlid!. Vestmannaey!. Rather frequent in the South-western and South-eastern parts of Iceland. It has been found almost everywhere on tuff-rocks, where it •/ THE BRYOPHYTA OF ICELAND 537 occurred abundantly in several places, for instance in Esja, but only sterile specimens were found. 304. Hypnum callichroum (Brid.) Br. eur. Stcrcodon callichrous Brid. E. Iceland: Seydisfjordur!. NW. Iceland: Common everywhere!. W. Iceland: Budahraun (H. J.)!; Grundarfjordur (H. J. ! , common every- where in the lava-fields east of Reykjavik and around Hafnarfjordur!; Svinahraun ! ; Esja, in Grz/mnz'a-heath at an altitude of about 400 metres, and in many places along the banks of streams!. S. Iceland: Skalholt!; Thingvellir! ; Holt!, common on tuff-slopes in clefts. This species is common in the south-western part of Iceland, and very common in North-west Iceland. In North Iceland it has not been found, and in East Iceland only near Seydisfjordur. It occurs in Ice land in two forms. The most frequent form is the typical bog-soil form, which is exceedingly common especially in NW. Iceland, and sometimes forms the bulk of the vegetation in damp situations, especially along streams, on wet slopes and at the edge of bogs, usually in association with Harpanthus, Lophozia quinquedentata , Cephalozia bicus- pidata, etc. Around Isafjordur it occurs up to a height of about 300 metres, and in S. and SW. Iceland up to almost 500 metres above sea-level. Everywhere in the depressions and at the bottom of the clefts of the lava-fields of South-western and West Iceland a mesophilous form is found, which is distinguished by its size and by its almost regularly two-rowed ramification. It grows in deep, loose and soft cushions, either among grass or mixed with Hylocomiuni spp., Rhacomitrinm hyp- noidcs and species of Dicranum and of Lophozia. Fruit was collected only in Kaldalon in NW. Iceland: it was quite undeveloped even at the end of June. 305. Hypnum Lindbergii Mitten. Stcreodon arcnatiis Lindb. Verv common. mj This species grows on wet ground, especially in bogs, associated with H. reuolvens. H. ciispidatum, Hylocomiam s0 me- tres; Dvrafjordur!, up to about 200 metres. S. Iceland: Widely distri- buted!; Thingvellir!; Laugardalur !. Widely distributed in the whole of the southern and south-western part of Iceland as far as Borgarfjordur and Snaefellsnes. It also occurs rather plentifully in some of the fjords of the north-west. It grows sometimes in clefts among fallen blocks of rock, sometimes on slopes together with other Hijlocomiiim spp.. Dicranam scoparium , Rhacomi- trium spp., etc., or in the birch coppices. It was collected in fruit near Holt in S. Iceland, where a few old, empty capsules were found. 324. Hylocomium triquetrum (L.) Br. eur. Iceland (Koenig). E. Iceland: Frequent from Berufjordur south- wards!. N. Iceland: Asbyrgi!; near Eyjafjordur (O. D.;!); Ljosavatn i Grl. ;!); common west of Blondudalur!. NW. Iceland: Rather common in all the fjords !. W.Iceland: Rather common everywhere (Grl.;!). Vest- mannaey!. S.Iceland: Common!. Commonly distributed from Berufjordur in E. Iceland throughout the whole of S., SW. and W. Iceland, and in the majority of the fjords of the north-west. It is rather rare in North Iceland proper, east of Blondudalur, and occurs, as a rule, only scantily in the coppices or in the Betnla nana heath. Its growth is similar to the other species of Hylocomium, with which it is almost always found associated, especially in coppices and on moss-grown slopes. It has the same altitudinal distribution as H. loreum and H. parietinum, as it hardly ascends higher than to the upper limit of the birch. In Esja it is common up to 350—400 metres, near Kolvidarhol it was found in company with H. loreum at 350 metres, and in NW. Iceland it everywhere accompanies the birch to its upper limit at about 250 metres. Only sterile specimens have been found. 325. Hylocomium squarrosum (L.) Br eur. Very common over the whole of Iceland. It grows both on a damp substratum, on stony flats as on boggy ground, and on a more dry substratum, associated with other Hijloco- minm spp., Hyp mini iincinatum, etc. It is most frequent in the low land, but occurs, however, also at rather considerable altitudes. In Berufjardarskard it was found even at 500—600 metres, near Dyra- fjordur at 330 metres and in S. Iceland in many places up to about 544 A. HESSELBO 500—550 metres above sea-level. Only sterile specimens have been found. 326. Hylocomium rugosum (Ehrh.) De Not. Widely distributed on dry grass or moss-grown slopes or flats, usually mixed with other Bryophyta such as Hylocomium parietimim, H. prolifemm, H, squarrosum, Rhacomitrium hypnoides, Dicranum scoparinm. Ptilidinm ciliare, etc., rarely unmixed in large mats. It has the same altitudinal distribution as H. triqiietrnm , and hardly ascends higher than about 300—400 metres above sea-level. Only sterile specimens have been found. II. THE BRYOPHYTE COMMUNITIES. A in the other Arctic and Sub-arctic countries, the Bryophyta play a very important part in the plant-covering of Iceland. They occur either as an essential component of, so to speak, all plant associations, and often in far greater numbers as regards species and individuals, than do the higher plants, or as distinct Bryophyte associations from which other plants are entirely absent, or in which they occur only as a subordinate component. As a basis of classification it comes natural to distinguish between (1) Lowland Formations and (2) Highland Formations. Within these two main groups the formations are again arranged according to their water-requirements, commencing with those which are the most water-loving. Naturally, no sharp limit can be drawn between these formations; on the contrary, all possible transitions between them are constantly met with, which makes a comprehen- sive survev extremelv difficult. In addition to this, the invesliea- «. *• tions are in many respects very incomplete, especially with regard to the history of development of the Bryophyte associations. Also, several of the formations occur both in the Highlands and in the Lowlands. This is especially the case with decidedly xerophilous formations like the Rhacomitrinm heath and, partly, also other moss-heaths. Mountain plateaus and slopes situated above the growth-limit of the birch and the heather moor are in this paper considered as be- longing to the Highlands (the Alpine Region). The limit in question may lie at various levels and can, of course, never be drawn sharply, but is in many cases dependent on the structure of the mountains. The flat land along the coasts and at the bottom of the vallevs rises, as a rule, in terraces inwards towards the high •/ 546 A. HESSELBO land. As far upwards as about 200- -400 metres the slopes and flats are covered with heaths and birch-coppices or bogs respec- tively. Then usually follow steep, bare slopes of gravel or abrupt cliffs, and the plateaus which follow these bear the scanty plant- covering of the rocky flat. The conditions, however, differ somewhat in different parts of the country. In NW. Iceland there is almost no low land with the exception of the narrow stretch of coast along the narrow, deep fjords. The steep, often vertical cliff-faces rise to a height of 500- (500 metres and have a talus of debris (Urd) at their foot, and cliffs rising in terraces occur almost exclusive!}7 at the head of some of the fjords. The entire surface at the top of the mountain belongs to the rocky flat, and the associations characteristic of the latter often occur on the slopes and flats right down to the level of the sea, especially on slopes facing north. In S. Iceland, on the other hand, in sheltered valleys, localities are met with as far upwards as 500 — 600 metres above sea-level, which, according to the composition of the plant-covering, must be referred to the Lowland formations. I. THE LOWLAND FORMATIONS. The Littoral Bryophyte Vegetation. There are only very few species which are restricted lo the immediate vicinity of the sea, or which grow by preference in the neighbourhood of the coast. Schistidinm maritimnm and Ulota phyllantha doubtless occur wherever there are rocky coasts, and are rarely found many hundred metres from the coast. They chiefly occur along the sea-coast itself, and at the entrance to the larger fjords, and decrease in frequency inwards towards the head of the fjord. Near Berufjordur, for instance, both species are very common around Djupivogur, but are entirely absent from the inner part of the fjord, and this is also the case in Seydisfjordur. Around the broad Isafjordur they are common as far inwards as Arn- gerdareyri, but are, as a rule, absent from the narrow branch-fjords. Both species grow on the coast rocks, but also frequently descend to the ground. On the island of Vestmannaey Ulota was very common on knolls in fields, where the grass-covering had been torn up by the wind, and Schistidium maritimnm has been found in several places on damp sandy soil. THE BRYOPHYTA OF ICELAND 547 Orthotrichum Blyttii occurs here and there on coast rocks, or at any rate in the immediate neighbourhood of the coast. Pottia Heimii is commonly distributed along all flat coasts and Amblystegium littorale occurs here and there on damp sandy soil. Besides these littoral species proper, there are several others which occur especially abundantly on the coast, but are also distri- buted in many other localities. Bryum argenteum and B. capillare grow especially below cliffs inhabited by sea-fowl , but their pre- sence there is, no doubt, as much due to the abundant supply of organic manure at to the proximity of the sea. Desmatodon lati- folius, Leptobryum pyriforme and Tortilla rnralis are also typical of damp sandy soil and Hypnum polygamum of saline, boggy soil. On damp sandy soil on the beach low, scattered moss-cushions consisting of stunted individuals of many different and more casual species are often met with, for instance, Distichium montannm, Di- dymodon rubelliis, Ceratodon pnrpiireus , Encalypta rhabdocarpa, Myurella julacea, Bryum spp., etc. Hydrophilous Bryophyte Formations. The water originating from rain and mist or from melting snow will, according to the local conditions and the inclination, either spread out over the ground and if it consists of humus or sand - - sink into it, or seek outlets in brooks and rivers. Where the water remains standing without being able to find a sufficient outlet, a bog vegetation is developed, or, in deeper hollows, a lake is formed. Part of the water which sinks down to the solid rocky substratum continues its way downwards along the latter until it sooner or later issues as a spring. Stagnant water contains humus substances, is not wrell aerated, and is warmed by the sun, while running water, both in streams and springs, is pure and clear and contains oxygen and carbonic acid. Running water has a very low temperature during the summer, at the most 4° — 6°. Therefore the composition of the vegetation on boggy ground differs entirely from that on ground along streams and near springs, inundated or saturated by the pure water. The hydrophilous formations may be classified as follows: 548 A. HESSELBO A. The Bryophyte Vegetation of Pure Water. a. The Bryophyte Vegetation of Running Water and of Lakes. b. The Bryophyte Vegetation of Inundated Gravelly Soil (slightly inclined ground and banks of streams). c. The Bryophyte Vegetation on Muddy Soil near Springs (Dv). B. The Bryophyte Vegetation of Boggy Soil1. C. The Bryophyte Vegetation of Damp Sandy Soil. D. The Bryophyte Vegetation near Hot Springs. The Bryophyte Vegetation of Running Water and of Lakes. The Bryophyte Vegetation of Lakes is extremely scanty, and often entirely absent. Along the shores of shallow lakes the surrounding swamp-vegetation may extend right into the water, especially species such as Hypnum giganteum, H. exanmilatam and //. scorpioides , while rocky shores are usually quite bare of sub- merged Bryophyte vegetation or bear, here and there, one or other of the species growing in streams, such as Fontinalis antipyretica or a //ypnum-species. How far Bryophyta (for instance, Fontinalis) may occur in deeper water has not been investigated. Glacier- rivers, on account of their torrential current and changeable course, as well as of the low temperature of their clay- containing water, are entirely devoid both of Bryophyte vegetation and of higher plants. Brooks and Rivers. Where the bottom consists of loose gravel and smaller stones which are kept by the water in constant motion, Bryophyte vegetation is entirely absent. But if the bottom is of firm rock or larger stones it is, as a rule, covered with ex- tensive moss-carpets which usually consist of Hypnum ochraceum or Fontinalis antipyretica, which may, either separately or together, cover large areas of the bottom. In very strong currents H. ochra- ceum forms the highly elongated and often thread-like var. filiforme which, together with Rhynchostegium rnsci forme var. atlanticum, is a characteristic species of torrential rivers on much inclined ground. H. ochraceum var. filiforme is found especially in larger streams, where it is then the only species occurring, while Rhynchostegium 1 In this paper no distinction has been made between swampy soil, marshy soil and boggy soil, the term "boggy'' includes all three kinds of soil. The Danish term in all three cases is "sumpet". THE BRYOI'HYTA OF ICELAND 549 appears to prefer smaller rivers with large loose blocks of rock al the bottom. Several other Bryophyta occur either mixed with the above or occasionally as dominants in the Bryophyte vegetation. Schistidium rivnlare is very common and often occurs abundantly. Hypnnm dilatatum, H. alpinum and H. alpestre are common in the northern and eastern parts of the country, but are absent from or are rare in other parts. In the river Ellidara near Reykjavik the bottom was in several places covered with Fontinalis androgyna. In shallower water, and especially on inundated rock- surfaces in waterfalls, several other species also occur. Almost everywhere in such localities are found: Haplozia cordifolia, Scapania undulata, Brachythecium rivnlare, Rhynchostegium rnsciforme , Hypnnm pcdustre, H. falcatnm, Philonotis fontana, Mniobnjnm albicans var. glacialis, Brynm Diwalii and Brynm ventricosum together with some of the species which thrive best in places where they are outside the water during a part of the year. Siones and rocks which protrude above the surface of the water and are inundated only during specially high water-levels are usually covered with a dense moss-carpet consisting of nume- rous species. In addition to the majority of the species of river- bottoms there occurs also an abundance of those belonging to damp rocks. Among the species which are rarely absent from such lo- calities may be mentioned: Hypnum falcatnm, H. filicinnm , Schisti- dium riuulare, S. gracile, Rhacomitrium aciculare, R. sudeticum, Blindia acuta, Dichodontium pellucidum, Amphidinm Mougeottii, Haplozia atrouirens and Mnium pnnctatnm., and in North and East Iceland, in addition to the above-mentioned, Philonotis seriata and Hypnum decipiens are to be found. A somewhat different vegetation occurred in the river Rekyirdalsa in SW. Iceland, which is so well supplied from hot springs that in the beginning of June the water had a temperature of about 12°, while that of the streams flowing into it on both sides was only 4° — 5°. Hypnnm ochraceum, which is else- where so common, was entirely absent, and Schistidium rivnlare *j occurred very scantily. On rock-surfaces and larger stones Hypnnm palustre, Brachythecinm riuulare and Rhynchostegium rnsciforme grew abundantly, the last had also set fruit. Fontinalis longifolia covered the bottom in many places, and on stones protruding above the surface of the water Hypnum filicinnm and Schistidium gracile were growing. In the cold tributary streams the usual vegetation occur- 550 A. HESSELBO red, consisting of Hypnum ochraceum, H.falcatum, Schistidinm ri- vulare, Rhynchostegium riisciforme var. atlanticum and Scapania undulata. The Bryophyte Vegetation of Inundated Gravelly Soil (slightly inclined ground and hanks of streams). Where the water flows down the mountain sides and spreads over slightly inclined gravelly ground, ,and along the flat banks of streams which are periodically inundated , a vegetation composed mainly of Bryophyta is developed. The most conspicuous spe- cies growing on this gravelly ground, and one which is hardly ever absent, and is often the most abundant constituent of the moss carpet, is Philonotis fontana, and after it this community may be designated the Philonotis association (Ostf., 1907). Very frequently many other species also occur, either as an ad- mixture in the Philonotis carpet, or replacing it over smaller or larger areas. In NW. Iceland P. fontana is often replaced by P. seriata. Mniobrynm albicans var. glacialis is almost as common as Philonotis; and Brynm ventricosum , B. Duvalii, Brachythecinm riuulare and Acrocladium cuspidatam are also among those species which are rarely absent. As a few examples will best show the composition of this ve- getation, the following are given: 1. The Ellidara near Reykjavik: The mossy fringe along the banks consisted of Philonotis fontana, Dichodontium pellacidum and Acrocladium cuspidahim. 2. Husavik, along a stream: A broad belt of Cinclidium stygium together with some Palndella squarrosa. 3. Husavik, along the banks of smaller streams on a slope: Mniobrynm albicans var. glacialis, Mninm punctatum, Philonotis fontana, Marchantia polymorpha together with some Brynm Duvalii and Thiiidinm lanatnm. 4. Berufjordur, along a stream: Philonotis fontana, Mninm Seligeri, Hypnum giganteum and Mniobryum albicans var. glacialis. 5. Svinaskard, along a small stream: Philonotis seriata, Scapania undutata, Chiloscyphns polyanthus and Pellia Xeesiana. 6. Kaldalon (NW. Iceland), in a small stream and on gravelly ground over which water was flowing: Philonotis seri- ata, P. fontana, Dicranella squarrosa, Mniobryum albicans var. THE BRYOPHYTA OF ICELAND ,"),")! iSj Brynm Duvalii, Chiloscyphus polyanthus var. fragilis, Harpan- thus Flotowiamis and Pellia Neesiana. 1. Kaldalon, along the banks of a stream: Hypnum calli- chroum, Sphagnum teres, Harpanthus Flotowiamis and Cephalo'ia bicuspidata var. Lammersiana. 8. Reykjavik, on ground over which water was flowing: slightly inclined surface with streamlets. The banks of the streamlets were fringed with Philonotis fontana, Mnibryum albicans var. gla- cialis, Brynm ventricosum, B. Dnualii and Acrocladinm cuspidatum. 9. Gnupsdalur (NW. Iceland), gravelly ground, over which water wras flowing, streamlets flowing down the sides of the valley: Philonotis seriata, P. fontana , Dicranella squarrosa, Haplozia cordi- folia, Chiloscyphus polyanthus var. fragilis, Scapania undulata and S. paludosa. Haplozia formed large black or greenish-black, and Scapania paludosa very large reddish-brown patches in the water, which was a few centimetres deep. In North Iceland several species of Hypnum occurred abundantly in gravelly soil over which water was flowing, and often formed pure Hypneta. Especially do Hypnum exannulatum var. piirpurascens, H. falcatum, H. decipiens and sometimes H. stramineum and H. sar- mentosnm occur in such localities. The Bryophyte Vegetation on Muddy Soil near Springs (D\). The bright-green moss-carpet around and below the point of issue of the springs described by Helgi Jonsson (1900, p. 24. 1895, p. 73) as moss bogs (Icelandic D\) are one of the most frequently occurring and characteristic plant communities of the Arctic and Sub-arctic regions. They were first mentioned by Gron- lund (1877, p. 330) as mats of sapgreen mosses along small streams on mountain sides, consisting of Bartramia fontana, Webera albi- cans, Brachythecium rutabulum var. rivulare and Hypnum uncina- tum , a. description which includes both the moss bogs and the moss vegetation along smaller streams, which have also much in common. Moss bogs develop in muddy soil, in all places where the ground water emerges as springs. They occur both on mountain slopes and at the bottom of valleys , occasionally also at higher levels, on rocky flats, but they are especially numerous on the lowest mountain slopes and in the flat boggy land below these 552 A. HESSELBO. slopes. There they lie irregularly scattered in bright-green patches, differing greatly in size, and conspicuous even at a distance bv their colour which is distinct from that of their surround- is ings. Higher up on the slopes at the foot of the bluffs, they fre- quently form continuous belts in connection with the mossy fringe along the downward - flowing streams (Helgi Jonsson, 1900, p. 25). The vegetation consists of nearly the same species as those found on inundated gravelly soil, and the external conditions for the plants are also essentially the same in both places, since it is the cold, well-aerated water which determines the composition of the vegetation. During summer the temperature of the water is usually only 4°— 5°, and this low temperature acts as a great check to the growth of higher plants, and is therefore indirectly favourable to the moss vegetation. The difference between the two vegetations is especially due to the substratum, that of the vege- tation of inundated ground and stream-banks consisting of gravel, while the moss bog developes on mud. For this reason also, some of the species which occur in the gravelly soil are absent from the moss-bogs proper, for instance Hypnum falcatum, H. decipiens, Di- cranella squarrosa, Philonotis seriata, Haplozia cordifolia, Scapania pahidosa and Chiloscyphus polyanthus var. fragilis. On flat ground moss bogs are, as a rule, almost circular in shape, and the species are arranged concentrically around the point of issue of the spring, whence the water gradually oozes through the moss carpet, and spreads out over the surrounding boggy ground. On sloping ground the moss bog is usually oblong in shape, and the spring emerges at its upper end (Fig. 19). In the majority of cases the Bryophyte vegetation near springs (the Dy) is a Philonotis-Mniobryum association, in which other species of Bryophyta and a few higher plants occur scattered (Ostf., 1907, p. 69). On the soft mud around the point of issue of the spring - and often covering the latter - Mniobrynm albicans var. glacialis usually grows, and outside the latter there is a broad belt of Phi- lonotis fontana, which may be intermixed with or replaced by other mosses; and scattered in the moss carpet are a few flowering plants and vascular cryptogams, especially Montia rwularis , Saxifrage stellaris, Epilobinin spp. and Eqnisetam palnstre. THE BRYOPHYTA OF ICELAND 553 Fig. 19. Kaldalon (NW. Iceland). Slightly inclined ground below the stony slope. The light-coloured stripes are moss bogs, the darker, boggy ground or. on somewhat higher levels, patches covered with Vaccinium-Empetrum heath. Besides the above-mentioned mosses the following plants are characteristic of the moss bog: Brachythecium rivulare Acrocladium cuspidatum Hypnum Kneiffii Bryum ventricosum B. Duvalii Mnium punctatum M. Seligeri M. cinclidioides M. affine var. elatum Marchantia porymorpha Pellia Neesiana But also other Bryophyta from bogs may occur intermixed with these, especially towards the edge, where the moss bog gradu- ally passes into the common bog-vegetation. But of course all pos- sible transitions also occur, between moss bog and bog vegetation as well as between moss bog and the vegetation of the banks of streams, all according to the nature of the underlying substratum. As some examples will best show the composition of the moss bogs, the following are given: 1. Seydisfjordur, numerous moss bogs on an almost hori- 36 554 A. HESSELBO zontal, boggy surface, below the slope of the mountain (Fig. 20), The vegetation was almost identical in all of them : In the middle, Mniobryum albicans var. glacialis was found intermixed with Montia rivalaris, then came a belt of Philonotis fontana, often greatly inter- mixed with Marchantia polymorpha and with scattered plants of Saxifraga stellaris, Eqiiisetnm palustre and Epilobium spp. In some moss bogs a pure Hypnetum composed of H. exannulatum var. purpurascens or H. Kneiffii had been developed. Fig. 20. Moss bog near Seyclisfjordur. The light-coloured patch in the middle is Mniobryum dlbicans var. glacialis. In the foreground and on the sides Philonotis f\mtana. 2. Husavik, moss bog on slightly inclined ground: In the middle Mniobnjiim albicans var. (jlacialis and Marchantia polymorpha were found, and around this a belt of Bryiim uentricosum f. major, Mnium affine var. elatum and Philonotis fontana, and outside it all an almost pure belt of Philonotis. 3. Breidabolstadr, slightly inclined grassland with scattered moss bogs : In the middle Mniobryum albicans var. glacialis grew inter- mixed with Brynm uentricosum f. major; around this was a belt of Philonotis fontana, and outside it all Mnium affine var. elatum and Acrocladium cuspidatum. Some smaller moss bogs below the slope THE BRYOPHYTA OF ICELAND 555 were composed of Brachythecium rivulare, Mniobrijnm albicans var. glacialis, Philonotis fontana, Brijum ventricosum, Mnium Seligeri and Mnium afflne var. elatum, which grew in patches intermixed. 4. Holt (S. Iceland), moss bog below a slope: Acrocladinm cuspidatum, Mniobryum albicans var. glacialis, Bryum ventricosum f. major, Mnium punctatum, M. Seligeri and Pellia Neesiana grew inter- mixed, sometimes as single plants and sometimes in patches. In the middle Montia rivularis grew among the mosses. The majority of the mosses growing near springs form special cold-water forms which are particularly characterized by their highly elongated, slightly branched stems of almost equal height, by which feature they all assume a homogeneous habit. Brachythe- dum rivulare forms a form with long, erects shoots of equal height and with appressed leaves. Philonotis fontana forms, when growing in very cold water, a highly elongated, hardly tomentose form with appressed, shortly pointed leaves with short leaf-cells and very broad nerve (forma adpressa). The cold-water form of Bryum ventricosum (f. major) is also higher in growth and more vigorous than is the bog-form, has steins bare of tomentum with large and broad, spreading leaves. Mniobryum albicans var. glacialis is also much more vigorous than the type, with larger and broader leaves. Mnium spp. develop elatum-forms with erect, sterile shoots of equal height. The Bryophyte Vegetation of Boggy Soil. The bog vegetation is extensively distributed about Iceland, especially in the low land, and in many places it occupies almost the whole tract of land between the mountain slopes and the sea. The lower mountain plateaus and slightly inclined slopes up to a height of about 300 — 400 metres are also to a great extent covered with bogs (Sedge-bogs). The mode of formation of these bogs has been described by Helgi Jons son (1895, p. 45). They originate partly from the further development of the vegetation of the springs and the banks of streams, and partly from shallow lakes first forming in depressions and afterwards becoming gradually filled up with plants in connection with sand transported by the wind. In the former case a drier bog (myri, pi. mvrar) is formed, the sedges superseding the mosses; in the latter case a wet bog (floi, pi. floar) is first formed, which, by gradually becoming overgrown with plants, develops into a "myri"1. 1 For a description of "myri" and "floi" see also Thoroddsen's Physical Geography of Iceland, ante p. 323. 36* 556 A. HESSELBO In "Die Moose des Sarekgebietes" (1910, p. 248) C.Jensen classifies the bog vegetation in four formations: The Willow bog, the Sedge bog, the Moss bog and the Peat bog. This classification cannot be entirely adopted as regards Iceland. Willow bogs proper (willow coppices in boggy soil) do not appear to be developed there. True, scattered individuals or small groups of Salix (S. lanata, S. phylicifolia and S. glaaca) are often found in the sedge bogs, espe- cially in NW. Iceland, but the moss vegetation there does not differ in any respect from that of the surrounding sedge bog. The vegetation of boggy soil is composed mainly of mosses and sedges, greatly varying in abundance. Sometimes the sedges are the dominant plants, and then the moss carpet is less conspicuous at the bottom, among the Carex and Eriophorum spp. ; sometimes there is a continuous moss-carpet in which the higher plants grow scattered, and then the one formation may be termed a sedge bog, and the other a moss bog, which, however, does not correspond with Helgi Jonsson's definition of a moss bog, but appears to agree with Warming's description (1887, p. 132). They are the same mosses which occur in the same manner in both formations, and all possible transitions are found between these. Helgi Jo nsson (1900, p. 20; 1905, p. 9) classifies the bog vegetation into Star-grass bogs and Moss bogs. The latter, which include the vegetation along streams, on inundated ground and near springs (Dy), and also some of the moss bogs in Warmings defi- nition, have been treated in the preceding section. The star-grass bogs are again divided into "Myrar" and "Floar". In the Mj'ri the ground water stands on a level with the surface, the soil contains acid humus and is so closely interwoven with rhizomes and roots that it bears one like a carpet. In the Floi the ground water stands above the surface, the soil is muddy and produces a more scattered vegetation of Carex and Eriophorum tufts. As it is chiefly the height of the ground water which determines whether a Myri or a Floi is developed, and the Floi is formed by the filling up of a shallow lake, there occur all transitions between lake and Floi, and through further development, between Floi and Myri. The Floi is poor in mosses. The soft muddy soil is not favourable to their growth, and it is only as an exception that some of the species are found which grow along the banks of lakes, but often the moss-covering is entirely absent. Hypnum scorpioides and H. giganteum are the most frequent species which THE BRYOPHYTA OF ICELAND 557 occur everywhere in pools and channels. Hypnum exannulatum, H. revolvens var. Cossoni and Acrocladium cuspidatum are also frequent. In man}r places in East Iceland Cinclidium styginm was found abundantly in Floar, while Hypnum cordifolium and H. fluitans were found in a few places only. The moss- covering of the Myri is characterized by the fact of its being rich in species, which grow sometimes greatly intermixed, sometimes separately in large and small patches. The ground is usually knolly, and there is a great difference in the vegetation between and upon the knolls, the most hygrophilous species growing on the wet ground between the knolls, while on the top of the knolls mesophilous and xerophilous forms are met with, and be- tween these all transitions occur, according to the height of the knoll and the degree of moisture. They are nearly the same species which are everywhere the most abundant constituents of the Myri vegetation. The following species occur on the ground between the knolls: — Musci veri *Hypnum revolvens intermedium stramineum stellatum poly ga mum sarmentosum Lindbergii exannulatum giganteum Richardsonii falcatum trifarium turgescens *Camptothecium nitens *Brachythecium rivulare *NE.) Thuidium lanatum *Acrocladium cuspidatum *Philonotis fontana *Meesea trichoides Sph agna *Sphagnum teres rubellum Warnstorffii fimbriatum medium Girgensohnii * snbnitens Meesea triquetra *Paludella squarrosa *Catoscopium nigritum *Cinclidium stygium *Mniurn cinclidioides punctatum affine Seligeri subglobosum *Brvum ventricosum k> *Splachnum vasculosum sphaericum *NE.) Dissodon splachnoides *Oncophorus \Vahlenbergii virens Dicranum angustum *Fissidens osmundoides *Dichodontium pellucidum Campylopus Schimperi Sphagnum papillosum inundatum squarrosum acutifolium riparium Lindbergii 558 A. HESSELBO Hepaticse *Pellia Neesiana *Lophozia quinquedentata *Aneura pinguis quadriloba multifida Schultzii *Cephalozia bicuspidata Hornschuchiana pleniceps *Scapania irrigua *Cephaloziella Hampeana uliginosa rubella undulata Odontoschisma elongatus *Blepharostoma trichophyllum *Alicularia scalaris *Anthelia julacea *Lophozia Kunzeana In the above list an asterisk is prefixed to those species which are common over the whole of Iceland, and which are met with in almost every considerable boggy tract. Some of the species are common in some districts and absent from others, for instance Thuidium lanatum and Dissodon splachnoides, which are very com- mon in North and East Iceland, but are rare or entirely absent from other parts of the country, and Campylopus Schimperi, which is found only in the southern part. The mosses often grow so much intermixed that a small collec- tion may contain 15 — 20 or even more species, but often smaller and larger patches are found dominated by a single species. Thus Catoscopium, Philonotis} Cinclidiam or Mnium bogs occur, in each of which one of these species is the dominant member. On very damp ground the mass of the vegetation is formed by, for instance, Mnium cinclidioides or Cinclidium stygium, and in South Iceland by Mnium Seligeri. In North and East Iceland it is especially Thu- idium lanatum which is often the most conspicuous species. Sphagnum spp. grow almost alwrays in scattered tufts, and Sphagnum bogs proper are rarely met with. Helgi Jonsson (1900, p. 25) records such bogs from Snsefellsnes, where they oc- curred on sloping ground and were composed of Sphagnum teres, S. Warnstorffli and S. Girgensohnii intermixed with Paludella squar- rosa, Hypnum stramineum, Hylocomium squarrosum and Polylrichum commune. I have only seen a similar vegetation near Barkarstadr in South Iceland, where, on a wet boggy slope stretching down towards a river, there was an almost continuous growth of Sphag- num rubellum and S. Warnstorffli intermixed with a few other mosses, especially Thuidium lanatum, Hylocomium squarrosum and Hypnum stramineum. Sphagnum spp. often play an important part in the knoll- formation of the myri, the large Sp/iagrnu/n-cushions being inter- THE BRYOPHYTA OF ICELAND 559 -woven with mosses and hepatics, and dilTerent plants such as Vaccinium spp., Betnla nana, Comanun palustre and several Car ices then establishing themselves upon these cushions. The numerous hepatics which occur are everywhere found interspersed in the moss carpet, especially in that upon the knolls, and, as regards all the species mentioned below, doubtless also in the ground vegetation between the knolls. The Bryophyte Vegetation of Knolls1 is dependent upon the varying degree of moisture, which is greatest on the ground between the knolls and least in their uppermost part. Some of the Bryophyta of the ground do not ascend higher than to the base of the knolls, while others, especially many of the pleurocarpous mosses, occur with equal frequency upon and between the knolls. In addition to the latter mosses the following species are found upon the knolls: *Hypnum uncinatum *Mnium hornum imponens *Rhacomitrium canescens *Climacium dendroides hypnoides "Hylocomium squarrosum *Ditrichum flexicaule parietinum *Dicranum scoparium proliferum congestum Orthothecium chryseum (N. Icel ) elongatum *Polytrichum alpinum *Lophozia lycopodioides strictum *Plagiochila asplenioides juniperinum *Ptilidium ciliare, *Aulacomnium palustre -and besides these, numerous other species which belong to other formations and must rather be regarded as casual visitors. The following examples will show the composition of the bog vegetation in the different parts of Iceland : 1. Skalholt in SW. Iceland. The country here over a wide •expanse is covered with vast boggy areas in which small, protrud- 1 According to my observations these knolls are formed either by soil accu- mulating in tufts of Sphagnum, etc.. in which other plants take root, among others sedges, when soil again accumulates, or by soil accumulating directly around roots of sedge-tussocks. This accumulation of soil and plants continues till big knolls are formed, some 60 — 70 cm. in height. These knolls occur in all stages of development, from tufts or tussocks with a slight accumulation of soil around their roots to completely rounded knolls in which the tussocks have en- tirely disappeared. In Danish "Tue" stands both for "knoll" and for "tuft" and ''tussock'1, which is very convenient when referring to one of the various stages of these "knolls". But the rendering into English has been difficult, though in each case the term most appropriate to the stage of development of the "knoll'" has been carefullv chosen. 560 A. HESSELBO ing masses of rock (holt) occur scattered. In the wettest parts of the myri grew Hypnum scorpioides, H. giganteum and some H. re- volvens v. Cossoni. The moss-covering of the ground between the knolls consisted mainly of Hypnum revolvens, H. stellatum, H. Lind- bergii, H. stramineum, Acrocladium cuspidatum, Hypnum polygamum, Hylocomium squarrosum, Camptothecium nitens, Mnium Seligeri, M. cin- clidioides, Philonotis fontana and Bryum ventricosum, all of which grew intermixed. Of more scanty occurrence were Hypnum sarmentosum, Paludella squarrosa, Meesea trichoides, M. triquetra, Cinclidium stygium, Mnium punctatum, Splachnum vasculosum , S. sphcericum, Fissidens osmundoides, Oncophorus Wahlenbergii, Alicularia scalaris and Aneura pinguis. The following hepatics grew both between and upon the knolls: Lophozia Kunzeana, L. quinquedentata, Scapania irrigua, Cephalozia pleniceps, C. bicuspidata and Cephaloziella Hampeana. The knolls were usually formed by Sphagna, especially by S. teres, S. Warnstorffti and S. rubellum, and in very wet parts of the m\ri also by S. medium. Woven into and above the Sphagnum-cushions grew Hypnum uncinatum, Hylocomium squarrosum , H. proliferum, H. parietinum, Climacium dendroides, Aulacomnium palustre, Dicra- num scoparium var. turfosum, Ptilidium ciliare, Plagiochila asplenioides, and, uppermost, Rhacomitrium hypnoides and R. canescens. 2. Hoskuldstadr in E. Iceland. Knolly sedge-bogs with a rich vegetation of mosses between the knolls, along the river at the bottom of the valley. The moss carpet of the ground between the knolls consisted of Hypnum revoluens, H.giganteum, H. stellatum, Acro- cladium cuspidatum, Mnium cinclidioides, Cinclidium stygium, Mnium affine var. elatum, Paludella squarrosa, Philonotis fontana, Meesea tricho- ides, M. triquetra, Bryum ventricosum, Aulacomnium palustre, Catoscopium nigritum, Oncophorus Wahlenbergii, Dichodontium pellucidum and Aneura pinguis. All the Bryophyta, as a rule, grew intermixed, but some of them frequently formed large, pure growths, especially Catoscopium nigritum and in the wettest parts Mnium cinclidioides and Cinclidium stygium. Upon the knolls, which were sometimes formed by Carex, sometimes by Sphagnum, grew Camptothecium ni- tens, Thuidium lanatum, Hypnum stramineum, H. uncinatum, Hylo- comium squarrosum, Sphagnum teres, S. Warnstorffii , and, upper- most, Hylocomium parietinum, H. proliferum , Dicranum scoparium, Rhacomitrium hypnoides and Scapania curta. Woven into the moss- covering, especially into that upon the knolls, were found Lophozia Kunzeana, L. quinquedentata, Scapania irrigua, Blepharostoma tricho- THE BRYOPHYTA OF ICELAND 561 phyllum, Plagiochila asplenioides , Cephalozia bicuspidata and C. Hampeana. The two sedge bogs described above may be regarded as types, and by far the greater majority of the sedge bogs have very nearly the same vegetation. 3. Breidabolstadr on Fljotshlid (S. Iceland). A flat, boggy tract of meadow-land beneath the low mountain-slope, inter- sected by ditches and, lowest of all, by a low dike in order to keep the water-level at a suitable height. The ground was even, without knolls, and covered by a vigorous vegetation of Carices, with a moss carpet at the bottom. Occasionally there were also patches where the moss-covering was dominant, and the species of Carex occurred in this as scattered individuals. The species were comparatively few in number and were usually dominant in spots. The most frequent species were Philonotis fontana , Mnhim Seligeri, M. cincli- dioides, Cinclidium stygium , Bryum ventricosum and Acrocladium cnspidatiim. Here and there patches occurred with a more mixed vegetation, which, in addition to the plants mentioned above, con- sisted of Hypnum revolvens, Meesea trichoides, Splachnum vasciilosum, Lophozia quinquedentata, and perhaps of several other species. Here and there were tufts formed by Sphagnum rubellum and S. teres. A vegetation of about the same composition as that described above is very commonly met with in South Iceland, where tracts of meadowr-land, by means of draining, irrigation or damming up, are kept at about the same ground-water level during the whole summer. The knolls disappear or are not formed and the moss-covering becomes poorer in species. 4. Ljosavatn in North Iceland. A rather large sedge bog on very wet ground, on the slightly inclined slope of the moun- tain. The moss-carpet was composed of Cinclidinm stygium, Mnium cinclidioides , M. Seligeri, Paludella sqnarrosa, Camptothecinm nitens, Hypnum spp., Philonotis fontana, Bryum ventricosum, Thuidium lanatum, Lophozia Kunzeana and L. quinquedentata. Sphagnum rubellum, S. teres, S. Warnstorffii and 5. Girgensohnii occurred abun- dantly in large tufts. In the wettest parts, where the water reached above the surface, grew thick, extensive carpets of Hypnum exan- nulatum, H . sti amineum , H. sarmentosum , H.giganteum and H. Ri- chardsonii, all in very vigorous development, and in fruit. The Hypnacece sometimes grew intermixed, but usually they occurred separately, and were only slightly mixed with other Bryophyta and CyperaceaB. This formation corresponds undoubtedly with C.Jen- 562 A. HESSELBO sen's Amblystegium-bog (1910, p. 253) and occurs rather commonly in North Iceland, but more rarely in the other parts of the country, probably because in North Iceland the climate is more continental than in the rest of Iceland. These moss bogs are most frequently composed of Hypnacece, but often Paladella squarrosa, Cinclidinm stygium or Mniam cinclidioides forms an essential part of them. 5. Isafjordur. The narrow strip of land, below the steep moun- tain slope (almost 600 metres in height) along the western side of the fjord, is covered with sedge bogs right to the head of the fiord. The most abundant constituents of the moss carpet between the knolls were Hypnum reuolvens, H. giganteum, H, exannulatum, Pala- della squarrosa, Philonotis fontana, Mninm cinclidioides, M. panctatum, Cinclidinm stygium and Brynm ventricosum. Here and there in the moss carpet grew Thnidium lanatnm, Catoscopiiim nigritnm, Meesea trichoides, M. triquelra (scantily) and Oncophorns Wahlenbergii. Splach- num sphwricum and S. vascnlosnm grew on cow-dung. The knolls were formed by Sphagnum leres, S. Warnstorffl, Polytrichum striclnm, P. alpinum, Mninm hornum and Dicranum scoparinm. The following hepatics occurred woven into the moss-cushions:- Lophozia quin- quedentata, L. Kunzeana, L. Hornschuchiana, L. qnadriloba, Scapania irrigna, Blepharostoma trichophyllum , Harpanthns Flotowianus , Ce- phalozia pleniceps, Cephaloziella Hampeana and C. rubella. 6. Seydisfjordur. A boggy flat at an altitude of about 350 metres. The ground was covered with a blackish-brown moss carpet composed of Hypnnm giganteum, H. slramineum, H. sarmen- tosum, H. revoluens, H. Rich ardson ii, H. exannulatum and H. uncina- tum, occasionally alternating with patches of Mnium cinclidioides. Tufts of Sphagnum teres and S. Girgensohnii occurred frequently, and Splachnum vasculosum was common on dung. Carex spp. and Eriophorum were abundant without, however, occurring so densely as to cover the ground. This type of Hypnum bog, from which other plants are most frequently entirely absent, is common in North and East Iceland at elevations of about 200 — 500 metres, on flats where the snow lies long. The moss carpet is, as a rule, thin and bears distinct traces of having been long subject to the pres- sure of the snow-covering, the old stems being pressed closely together, and only the annual shoots growing up into the air. Peat Bogs. In the course of time sedge bogs usually develop into peat bogs. Gradually, as the peat layer becomes thicker, the dampness THE BRYOPHYTA OF ICELAND 563 of the surface decreases, the most hygrophilous species disappear and some other species, chiefly mesophilous, take their place.. Some of the latter are especially connected with this soil. The most marked species of peaty soil are Psilopilum Icevigatam, Polytrichum gracile, P. jimiperinum , Pogonatum polytrichoides, Mnium hornum, Catharinea undulata (also in warm soil) and Dicranella ceruiculata. Some species which occur on other soils, but most abundantly on peat, are Philonotis tomentella , Pogonatum urnigerum, Funaria hy- grometrica, many Bryum spp. (especially B. inclinatum, B. affine, B. arcticum, B.lacustre and B.pallens), Pohlia nntans, Leptobryum pyriforme, Distichium inclinatum, Ceratodon pnrpureus and Dicranella crispa. The above-mentioned species are all mesophilous, a few are xerophilous also (for instance P. jumper in am and Ceratodon), and the majority of them occur also in sandy soil, but in Iceland the peat is often abundantly mixed with fine sand , transported by the wind. The two rare species, Trematodon ambiguus and Pogo- natum capitlare var. dentatum, have also been found on peat. The most decided character-plant of peaty soil is Psilopilum Icevigatam, which occurs everywhere on peat-fla\s which have been laid bare, and may, for instance, entirely cover the piled-up heaps of cut peat with its numerous capsules, often in association with Funaria hygrometrica. Another characteristic vegetation of localities like these consists of extensive bluish-green mats of low-growing, sterile Pogonatum urnigerum, interwoven with Alicularia scalaris. The following examples will show the composition of the peat bogs in the different parts of Iceland: 1. Seydisfjordur. In a peat bog intersected by ditches: Psilopilum Icevigatum, Leptobryum pyriforme, Pogonatum urnigerum, Polytrichum jimiperinum and P. alpinum grew abundantly. Inter- mixed with the above occurred Bryum inclinatum, B. arcticum, B. purpurascens, Distichium montanum, Ceratodon purpureus, Scapania curta, Alicularia scalaris and Lophozia Wenzelii. 2. Akureyri. Behind the town, at the foot of the mountain, were large expanses of bogs from which great quantities of peat had been removed. The bared flats and the piled-up heaps of cut peat were often entirely covered with Psilopilum and Funaria. Commonly occurring species were Polytrichum gracile, P. alpinum, P. juniperinum , Leptobryum pyriforme, Bryum inclinatum, B. affine B. lacustre, B. arcticum, Philonotis tomentella, Ceratodon purpureus. Dicranella crispa, Didymodon rubellus and Scapania irrigua. 564 A. HESSELBO 3. Grunnavik near Jokulsfjordur. A deep layer of peat, here and there intersected with ditches. The following mosses were observed: Polytrichum alpinum, P. Swartzii, Mnium hornum, Pohlia nutans, P. cuciillata (both common), Bryum purpurascens, Ceratodon purpureus, Dicranella cerviculata, D. crispa, Lophozia quin- qaedentata and a few tufts of Tetraplodon bryoides. Psilopilum Icevi- gatum was found only scantily and after a long search. 4. Lundur in W. Iceland. On a damp peat-flat, the upper- most layer of which was pared off, grew Dicranella Schreberi, Aongstroemia longipes, Bryum lacustre, B. inclinatum , B. ceneum, Di- chodontium pellucidum, Philonotis fontana, Meesea trichoides and Aneura pinguis. The Bryophyte Vegetation of Damp Sandy Soil. The damp sandy or gravelly ground along streams, inundated only in the case of especially high water-levels, is often covered with a moss carpet of a very mixed composition. Here liverworts play an especially important part, and very frequently pure liver- wort associations are met with , or other associations in which the liverworts are almost dominant. They are almost everywhere the same species which are the most abundant constituents of the moss carpet. The following Hepaticce are the most frequent: Scapania subalpina, Alicularia scalaris, A. geoscypha, Lophozia quinquedentata Cephalozia bicuspidata var. Lammersiana, Anthelia julacea, A. Ju- ratzkana, and, especially in NW. Iceland, Harpanthus Flotowianus. Intermixed with the above occur a very great number of species of which the most frequent are Pellia Neesiana, Aneura pinguis, Haplozia atrovirens, Cephalozia pleniceps, Dicranella crispa, Dichodon- tium pellucidum, Aongstrcemia longipes, Didymodon rubellus, Disti- chium montanum, Pohlia commutata, P.gracilis, Bryum pallens, B. inclinatum, B. affine, Philonotis tomentella , P. fontana, Pogonatum urnigerum and Timmia austriaca. A few less common species, such as Blasia pusilla, Eucalyx subellipticus and Distichium inclina- tum, also belong to this community. Sometimes a moss-covering of another composition is also met with, Hhacomitrium canescens often forms extensive mats on wet sand}7 ground. In North Ice- land Timmia austriaca and Philonotis tomentella are found plenti- fully in many places on the damp ground above the Philonotis- belt, as a rule abundantly mixed with other species. Dicranella crispa is also very often found in great quantities on damp sandy THE BRYOPHYTA OF ICELAND 56.") ground. In North-west Iceland the development of the liverwort- mats was especially typical in many places (for instance in Gnups- dalur and near Isarjordur) ; they consisted chiefly of Harpanthus Flotowianus, Alicularia geoscypha, A. scalaris, Cephalozia bicuspidata var. Lammersiana and Lophozia quinqaedentata. Here Oligotrichnm hercyniciun also occurred abundantly in damp sandy localities. On a somewhat damp, cold flat at the bottom of the fjord Kaldalon, below the Jokull, grew Pohlia gracilis, Hypiuim exanna- latam var. brachgdictyon, Philonotis tomentdla and Encalyx subel- lipticus. The Bryophyte Vegetation near Hot Springs. Iceland abounds in hot springs: they are not, however, equally distributed over the whole country, but are most numerous in dis- tricts in which the most volcanic activity occurs. The majority of these hot springs are found in the south-eastern part of the country, on Reykjanes, around Reykjavik, in the south-western low land, and in several of the valleys of West Iceland, especially in Reykholtdalur. In North Iceland, the district around Myvatn is rich in hot springs, but they are also found scattered singly over the whole of this part of the country. They are absent from East Iceland, but a few occur in North-west Iceland, especially around Isafjardardjup. Groups of hot springs are found in several spots in the inner high land, but the Bryophyte vegetation around these is quite unknown. The majority of the hot springs of Iceland have a rather high temperature, the water being most frequently at about boiling point. Springs, the temperature of which is not much higher than that of their surroundings, are found for instance around Isafjardardjup near Laugarbol (50°— 55°) and Nauteyri (25°— 30°), yet no charac- teristic vegetation had developed there. According to Th or odds en such springs also occur north of Vatnajokull, and have a tempera- ture which is not many degrees higher than their surroundings. The hot springs in Iceland may be classified as belonging to two different groups, viz. the Alkaline Springs and the Sulphur Springs. The Alkaline Springs (thermae) usually occur in districts where there has been no recent volcanic activity. They contain pure, clear water which often deposits siliceous sinter, and are always surrounded by a luxuriant vegetation. When the temperature reaches 566 A. HESSELBO boiling point, they are called in Icelandic "liver" (plur. "hverar"), if the temperature is lower, they are called "laug" (plur. "laugar"). The Sulphur Springs (Icelandic "brennistenshverar") are most numerous in districts where the effect of the volcanic activity is still felt, for instance near Myvatn and in many parts of South Iceland. The water contains sulphuretted hydrogen. These springs deposit sulphur, and the soil around them is greatly decomposed by the acid vapours which arise, and is transformed to red or yellowish clay-masses. Sometimes, as for instance in Reykirdalur, they also deposit siliceous sinter. As a rule, a group of springs consists of either the one or the other kind of spring, occasionally, however, a few springs containing sulphuretted hydrogen may be found together with the alkaline springs. The vegetation around sulphur springs is always very scanty, since only a few species of plants can thrive were they are exposed to hot vapours containing sulphuretted hydrogen. The "Laugar" near Reykjavik. The vegetation has been described by Ostenfeld (Bot. Tid. , vol.22, pp.233 et seq.), wrho has not, however , mentioned the moss vegetation. When I visited the springs in 1909 and 1912 I found no characteristic moss vege- tation. Since the warm water had been used for washing purposes the ground surrounding the spring had been much trampled upon, and further downwards towards the warm outlet only the usual bog species were found. Here Philonotis fontana alone formed the elongated slender form known also from other hot springs. The Springs on Biskupstungur. On the low boggy tract of land between the rivers Bruara and Tiingufljot in South Iceland (Biskupstungur, so called because the old episcopal residence Skalholt was situated there), there are, on both sides, along the rivers several hot springs of considerable size, or groups of hot springs of which Thorlakshver and Laugarashver in the southern- most part, near Skalholt, and Sydri Reykjahver, further northwards near the Bruara, have been investigated. They all contain pure \vater free from sulphuretted hydrogen, with the exception of a few small holes near Thorlakshver. Thorlakshver (Fig. 21) is situated a few kilometres west of Skalholt, close to the east bank of the Bruara. It consists of one larger and several smaller holes, from whence the boiling water flows out and gathers together into a rather large brook, which tlows into the Bruara. The vegetation along the sloping THE BRYOPHYTA OF ICELAND 567 hanks of this brook and of the flat boggy surroundings (which are partly influenced by the heat of the soil, partly inundated by the hot water) is very luxuriant. Both around the basins of the springs and along the brook formed by the outlets of the springs, grew a Fig. 21. Thorliikshver near Skalholt. In the background the river Biuart'i: behind the fence to the left is a potato field, where the temperature of the ground was about 25°. The chief outlet of the spring is just behind the small elevation to the left, and the outlet-channel is from the right straight across the foreground. The ''peninsula", in the middle of the figure, surrounded by the hot water, is partly covered with Sphagnum (the light patch) and partly with //i/pm/m-mats (the dark patch). broad belt of enormous yellowish brown and pale-green Sphaynum- cushions, 25 cm. deep, chiefly formed by S. imbricatiim (yellowish brown), S. teres and S. cymbifolium (whitish green) interwoven with Hypnum stramineum, Hijlocomium squarrosnm and here and there with Acrocladium cnspidatiim, Hypnum imponens and H. Lindberyii. The 568 A. HESSELBO surface of the Sphagnum cushions was usually covered with the orbicular, closely appressed leaves of Hydrocotyle vnlgaris. The temperature in the Sphagnum cushions was rather high, on the surface of the ground as much as 50°, chiefly on account of their feeble heat-conducting power, and the tufts were quite saturated with the moisture from the warm vapours. The Sphagnum-belt did not extend so far as to the hot water, but everywhere there was a strip (10 — 20 cm. broad), nearest the water, covered with low dark-green mats of Fossombronia Dumortieri, occasionally intermixed with Haplozia crenulata or Alicularia scalaris. The same vegetation of Hepaticce was in fact found in all places where the banks were too steep to allow Sphagna to gain foothold. The temperature under the Fossombronia-covering was, as a rule, about 40° (34° -43°). Where the bank was flatter and on the warm, dry, clayey flats in the neighbourhood of the springs Archidium phascoides grew in great masses, and often formed, without intermixture of other species, extensive, dark-green mats, 1 — 2 cm. deep. It occurred also on the siliceous sinter deposited by the water, and here and there among the Hepaticce. The temperature of the soil under the Archidium-mat was almost everywhere about 40°. In the brook formed by the outlet of the spring there was a small island which was partially inundated by the hot water, and here grew a great manjr large cushions of a peculiar form, a Barbula fallax (var. Ice- vifolia n. var.), and in one spot, on the slope, in the neighbourhood of the basin, grew Anthoceros punctatus together with Fossombronia. Outside the Sphagnum-bell the ground was perceptibly warm even for a tolerable distance, and the vegetation there was likewise greatly exposed to the warm aqueous vapours. There Hypnacece, in particular, grew very luxuriantly on the rather dry substratum. Hypnum imponens and H. Lindbergii were often almost the only species to be found there, the latter growing in a peculiar, erect form, almost branchless. The temperature of the ground under the Hypnum-covering was, as a rule, 25° -30°. A little below the spring the brook flowed along a steep bank about a metre high. Here the Sphagnum-belt disappeared and was replaced by a more mixed vegetation. Lowermost, at a height of about 10 cm. above the water, grew Fossombronia, Haplozia crenu- lata, Alicularia scalaris, and Anthoceros, then followed thick cushions of Hylocomium squarrosum, Hypnum stramineum, Thuidium delica- tuliim, Sphagnum teres, 8. imbricatum and Catharinea undulata, THE BRYOPHYTA OF ICELAND 569 moreover, Haplozia sphcerocarpa woven into the Catharinea-cushions. All the mosses had developed to an unusual height and vigour, especially Catharinea which occurred in a peculiar form (f. thermo- phila) and formed large cushions more than 10 cm. deep. The same vigorous moss vegetation, associated with grasses and sedges, was also found on the flat above the steep bank, as far as the influence of the warm vapours was felt. Where the banks were low, so that the hot water partially flowed over and mixed with the cold water of the boggy ground, the usual bog or stream -bank vegetation was developed, which nearest to the outlet, in hot water of a temperature of about 25° 30°, consisted of a very slender form of Philonotis fontana, associa- ted with some Hypnum stramineum and Catoscopium nigritum. The Hypnum-be\\. mentioned above gradually merged into the usual grassland vegetation; most of the species of which (for in- stance Rhacomitrium canescens, R.hypnoides, Philonotis, Mniobryum albicans and Hypnum uncinatnm) were also found intermixed with the thermophilous vegetation proper. A short distance from the main group of the hot springs, on a small, flat piece of ground near the river, there are some small holes, some of which emit boiling water, and some vapours im- pregnated with sulphuretted hydrogen. The ground around these holes consists of a rather dry, warm (30° -40°), clayey soil, with a very sparse vegetation. Archidium is common everywhere; Fossom- bronia often grows around the holes, and here and there on the clayey flats Riccia crystaUina and Anthoceros punctatns. Laugarashverir (Fig. 22) are situated in the southernmost part of Biskupstungur, near the farm Laugaras. At the foot of the slope on which the farm is situated, and in the boggy ground below, there issue several boiling hot springs which, through several channels, unite and form a large brook which flows into the Tun- gufljot. The vegetation is very much like that in Thorlakshver. Next to the water there is a belt of Fossombronia , Haplozia crenu- lata, Alicularia and Archidium with a ground temperature of as much as 43°; then comes the Sphagnum-belt which is composed of S. sub- nitens var. coerulescens , S.teres, S. an gusti folium, S. cymbifolium , S. imbricatum and S. inundatiim in association with Hypnum strami- neum. The warm ground between the channels was covered with extensive mats of Hypnum imponens, H. Lindbergh, H. stramineum, Hylocomium squarrosum , Climacinm dendroides, Thiiidium delicatu- The Botany of Iceland. Vol. I, part II. 37 570 A. HESSELBO /u/n, Calypogeia Trichomanis and Scapania irrigua. Aulacomnmm palastre was occasionally met with on wetter ground, and Archi- dium phascoides, Ditrichum homomallum and, on a single spot, Campylopus frayilis on rather dry, clayey soil. Under the Hyp- Fig. 22. Laugarashverir. The springs are situated at the foot of a hill : along the outlet-channel and next to the water there is a narrow, dark belt of Hepaticd- and Archidiuin, then conies a broad belt of Sphagnum-cushions, and outside that (the dark patch in the fore- ground) are ffypnum-carpets. n urn-mats there was an almost constant temperature of 32°, and under Archidium as much as 46°. On the slope above one of the largest springs Riccia sorocarpa grew in abundance, and where steep banks were formed along the outlets grew Hypmim, Thui- diam and Catharinea iindnlata f. thermophila ; as was the case near Thorlakshver. THE BRYOPHYTA OF ICELAND 571 Further northwards near the Bruara is Sydri Reykjahver. This consists of a large round basin from the centre of which the spring rises, bubbling up at short intervals and ejecting a consider- able amount of boiling hot water which flows over the edge of the basin and gathers together into a brook which flows into the river. On the somewhat higher and eastern side of the basin there is luxuriant grassland, while the lower western side bears a vigorous Bryophyte vegetation. Here, next to the water, grew extensive dark-green and reddish-brown mats of Alicularia scalaris, Haplozia crenulata and some Catoscopium nigritum in which bluish-green patches of Fossombronia occurred interspersed, and occasionally ro- settes of Anthoceros punctatns. Here the temperature of the ground was 25° -27 c just below the surface. Then followed a belt, about 2 metres broad, of Sphagnum papillosum, S. cymbi folium and fruit- ing specimens of Polytrichum commune, with a ground temperature of about 20°. Lowermost on the steep bank (50 — 70 metres high) along the outlet grew the usual belt of Hepaticce consisting of Haplozia, Ali- cularia and Anthoceros, then an abundance of Oligotrichum hercy- nicum interwoven with Haplozia sphcerocarpa, and uppermost along the edge large cushions of Hypnum stramineum, Hylocomium squar- rosum and some Sphagnum cymbifolium, and here and there Caly- pogeia Trichomanis. In a small bog by the side of the basin, into which the hot water no doubt frequently flowed, grew, in addition to the usual bog vegetation, numerous large cushions of Sphagnum teres and S. inundatum. The Hot Springs in Reykholtdalur. Throughout the whole of Reykholtdalur, on both sides of the river Reykjadalsa, there occur very many hot springs, some of which discharge a great amount of wrater. Near the vicarage of Reykholt rise Dynkur, Skribla, Snorralaug and other springs, which in part contain sulphuretted hydrogen. Some hundred metres more to the south, on the other side of the river, is Hagindishver, and farther down the valley are other hot springs, of which the largest are Deildatunguhver, Snseldubeinstadahver, Sturlurreykjahver, Klepp- jarnsreykir (probably Gronlund's Kleppholtsreykir) and Vellindis- hver; the last-mentioned is a fountain (gey sir), which is situated on a small rock in the river, and is quite bare of vegetation. The 37* 572 A. HESSELBO water in all these latter springs is pure and free from sulphuret- ted hydrogen. Near the springs around Reykholt the Bryophyte vegetation is rather scanty, partly on account of the sulphuretted hydrogen, and partly on account of the constant disturbances caused by the traffic and the use of the hot water. Sphagnum is practically ab- sent. Along the outlets of the springs liverworts grew almost ex- clusively. Fossombronia and Blasia pusilla were very common, the latter grew in the form of flattened rosettes. Haplozia crenulata and Alicularia scalaris were also frequent. Around all the other springs in Reykholtdalur there was a luxuriant vegetation of Sphagna. S. papillosum was especially do- minant and occurred in very large cushions, often 20 — 25 cm. deep, but besides this many other species were found either intermixed or separately in yellow, greenish, red or brownish cushions. The following species have been found on warm ground in Reykholt- dalur: Sphagnum papillosum, S. cymbifolium, S. angustifolium, S. ru- bellum, S. Warnstorffii and S. teres were all common, S. subnitens (fr.), S. acutifolium, and S. Dusenii var. falcatum occurred only now and then. The Sphagnum spp. grew partly as a belt along the outlets of the springs, partly on the boggy ground over which the hot water was flowing. Intermixed with these grew everywhere Hypnum stramineum, and in many places Polytrichum commune with ripe capsules. Near Snseldubeinstadahver Odontoschisma Sphagni was scantily woven into tufts of S.rubellum. The warm clayey flats next to the water, and especially the steep banks stretching down towards the outlets, were covered with a dense carpet of mosses and liverworts, in which the latter were usually in the majority. The bluegreen rosettes of Anthoceros were found almost everywhere, usually together with Fossombronia, Blasia, Alicularia scalaris and Haplozia crenulata. In such places A rchidium also often grew in great abundance. Gronlund records Catoscopium nigritum as occurring abundantly around hot springs in Reykholtdalur, but he has confused it with Archidium phascoides. Catoscopium is found only exceptionally, and, as it were, accidentally on warm ground, sometimes in a somewhat divergent, slightly tomentose form (var. Grdnlundii C. J.). On warm boggy ground the Sphagnum carpet was often greatly intermixed with, or partly replaced by, a Hypnum vegetation to- THE BRYOPHYTA OF ICELAND 573 gether with some other Bryophyta. Hypnum reuoluens, H. ex- annulatum , H. stramineum , H, stellatum, Acrocladinm caspidatum, Scapania irrigua, Pellia Neesiana and Alicnlaria scalaris were very common, Aneura maltifida occurred here and there, especially in the Sphagnum rubellum cushions. Where the ground was less damp, especially on slightly inclined slopes stretching down towards the hot water, it was covered with a thick carpet of Hypnnm im- ponens, H. molhiscnm , H. stramineum , H. revolvens , Hylocomium sqiiarrosum, H. parietinum, //, proliferum and Camptothecium lutes- cens, in which were scattered cushions of Sphagnum, especially S. rubellum and S. teres. Sometimes Preissia commutata also could form bluish-green patches, about a metre in breadth, usually inter- mixed with some Hypnnm molluscum. Sturlurrey kja hver is situated on a slightly inclined slope stretching down towards the river Reykjadalsa. At the top, near the spring, there is the usual Sphagnum vegetation which, farther downwards where the ground on both sides of the outlet of the spring is rather boggy, is replaced by a greatly mixed vegetation, composed principally of Hypiuim imponens, Hylocomium sqiiarrosum, Polytrichum gracile, Dicranum scoparium var. orthophyllum, Caly- pogeia Trichomanis and Alicularia scalaris. Alternating with the Hypnum carpet, extensive, dark-green mats of Archidium are found. The surface temperature of the ground under the Sphagnum carpet was, as a rule, 40°, whilst under the Hypnum- Archidium carpet there was an almost constant temperature of 37°. On stones in the tepid water, the temperature of which was at this spot 34°, grew large cushions of Dicranella squarrosa. Kleppjarnsreykir is undoubtedly the same spring that Gronlund (1877, p. 350) calls Kleppholtsreykir. He states that at this spring the same two species of Sphagnum occur that are found near Tiinguhver, and that near the spring and its outlet, among others, "Distichium capillaceum, Mnium serratum, Hypnum ochraceum and Catoscopium nigritum" are found. The two last-mentioned have been wrongly determined, and the two first do not at any rate be- long to the species characteristic of the warm ground. The outlet has for a tolerably long distance steep banks, about half a metre high, which are, at the foot, covered with the usual liverwort-vegetation: Haplozia crenulata, Fossombronia, Anthoceros, Alicularia and Archidium. The uppermost part is covered with a dense moss-carpet consisting of Hylocomium sqiiarrosum, H. proli- 574 A. HESSELBO ferum, Hypnum imponens, Mnhim hornum, M. undulatum, M.serra- tum, Fissidens osmundoides and Enthostodon ericetorum. On a stone partly inundated by the hot water, which had a temperature of about 50°. Fissidens osmundoides, Blindia acnta, Dicranella squar- rosa, Enthostodon ericetorum, Anthoceros punctatus, Aneura multiftda and Scapania irrigua grew intermixed. Fig. 23. Deildatunguhver. To the left is the slope with the hot springs. The part in the middle is saturated with the hot water and covered with Sphagnum papillo- sum, Polytrichum commune and Hydrocotyle. Deildatunguhver (Gronlund's Tunguhver) (Fig. 23) is situated north of the river and opposite to Kleppjarnsreykir. It is mentioned by Gronlund (1877, p. 349), who states that the surface temperature of the ground at the top of the hill was 23° R, and that there Polytrichum commune, Sphagnum cymbi folium, S. cuspida- tum and a Campy lopus (C. flexuosus) not determined with cer- tainty grew in the warm ground. Deildatunguhver is one of the hot springs of Iceland which discharge the greatest amount of water, and consists of a row of holes at the foot of a hill 6 — 8 metres high, whence an enormous quantity of water and steam is ejected with a great noise. The masses of steam, which can be seen for miles, enshroud the surroundings of the spring with so dense a cloud that it is hardly possible to ap- proach without getting soaked through. Below the hill the water THE BRYOPHYTA OF ICELAND 575 gathers into a broad brook which flows into the river. The whole hill, which consists of reddish clay, is warm throughout, and at the top the temperature was 06 3 40° just below the surface of the ground. On the slope stretching down towards the springs Hlasia pu- silla grew abundantly, occasionally in companjr with Fossombronia Dumortieri. The dry ground on the top of the hill was covered with large patches of Campijlopus flexuosiis and Hypinim imponens intermixed with scattered tufts of Catharinea undalata and Oligo- trichum hercynicum and entirely interwoven with Gymnocolea in- flata. At the foot of the hill, but on the opposite side to that on which the springs lie and where the ground was damper, grew, in addition to the above-mentioned species, Sphagnum cymbi folium and Polytrichum gracile. Here some 5 — 6 small plants of the fern Blechnum spicant were also found. The warm brook below the hill divides into several branches, which flow round some large islands saturating them with the warm water. Here Sphagnum papillosum, S. angustifolium and Po- lytrichum commune grew in enormous cushions, which were every- where covered by the orbicular leaves of Hydrocotyle vulgaris and entirely enshrouded in hot vapours. Geysir. On a low mound about one kilometre long and about Vs a kilometre broad, situated about 100 metres above sea- level, there are a great number of hot springs (about 40) besides the well-known Great Geysir. The majority of these springs con- sist of a larger or smaller hole, but sometimes of a basin, several metres in diameter, in which the boiling water usually reaches to the upper edge and flows over the somewhat raised rim, or is ejected at shorter or longer intervals. The soil consists of reddish clay, or nearest to the springs especially to Geysir of sili- ceous sinter. The water in the majority of the springs smells slightly of sulphuretted hydrogen. The whole district around the springs is warm, and in many places the temperature is so high that the tenants of the neighbouring farm (Laug) bake their bread by putting the dough into a pot and burying it about 30 — 40 cm. below the surface of the ground. The siliceous sinters are quite bare of vegetation. The warm clay-flats situated on a higher level are, as a rule, dry, and either bear a greatly scattered Bryophyte vegetation or are quite bare. Un- der the scattered, low cushions of Ditrichum homomallum, Archi- 576 A. HESSELBO dium and Fossombronia which were growing here, the thermometer showed as high a temperature as 34° on the surface of the ground. On a slightly damp flat which was covered with a low -growing, dense form of Climacium dendroides, the surface temperature of the ground was 43°. In the more low-lying tracts, where the ground was rather damp, or partially inundated with hot water, there had, in several places, developed a luxuriant vegetation of phanerogams and moss- es, which was, however, often much trodden down. Here, in the boggy parts, grew a low vegetation of Carex-Viola palustris, greatly mixed with Bryophyta, of which the following species, which grew intermixed, were observed: Hypnam stramineum , H. sarmentosum, H.imponens, Hylocomium squarrosum , Sphagnum cymbifolium, Ca- tharinea undulata, Calypogeia Trichomanis , Alicularia scalaris, Ha- plozia crenulata, Scapania irrigua, Aneura pinguis and an undeter- minable Pohlia. On damp clayey flats Archidium, Fossombronia Dumortieri, Haplozia cremilata and Alicularia scalaris formed low, dense mats in which Anthoceros punctatus occasionally occurred in small rosettes. Below Great Geysir, Hypnum chrysophyllum grew on a clayey flat inundated with tepid water. Laugarvatnshverir. By the shore of lake Laugarvatn, below the farm of the same name and along the water's edge, there is a row of springs containing boiling water saturated with sulphur- etted hydrogen. The surrounding ground which consists of black basalt gravel is, owing to its ex- posed situation, quite bare of Bryo- phyte vegetation ; and of higher plants only a few specimens of Polygonum Persicaria were found. By the northernmost of the springs only, which is situated at some dis- tance from the lake shore, a warm, damp clayey flat was covered with a carpet of Sphagnum cymbifolium, S. Girgensohnii, Polytrichum com- mune, Hylocomium squarrosum, Hyp- Fig. 24. Bryiim sp. «, Older leaves deve- num stramineum, Archidium phas- loped beforelhcplant wasinundatedwith Coides, Pohlia grandiflora $, Aong- hot water ; b, leaves from shoot developed a a strcemia longipes, Gymnocolea inflata in hoi water (Geysir). THE BRYOPHYTA OF ICELAND 577 c. coles., Haplozia sphcerocarpa, H. crennlata, Alicnlaria scalaris and Scapania irrigna. At Englandshverir, some small hot springs which rise in Lundurreykjadalur, there was only opportunity for quite a short stay on the journey past. Here, on the warm ground along the outlet of the springs the following species were observed: Sphag- num teres, Hypnum imponens, Catharinea undulata, Fissidens os- mundoides, Enthostodon ericetorum, Catoscopium nigritum, Archidinm phascoides, Aneura pinguis, Pellia Neesiana and Fossombronia Du- mortieri. The Hot Springs near Reykir. In the south-western part of Iceland, around the farms Revkir and Revkirfoss, about 45 kilo- »/ \j metres south-east of Reykjavik, there is a very large group of hot springs which stretches towards the north and north-west, through the valleys, right up upon Hen gill to a height of 400 — 500 metres above sea-level. To this group must also be reckoned the hot springs near Kolvidarhol and on Hellisheidi. The majority of the springs are situated around the farm Reykirfoss, and north of the latter, on both sides of the river from a height of about 50 to 90 metres above sea-level; most of them are in the neighbourhood of the river, and are in part situated directly upon the banks of the latter, several, however, lie upon the slope of Reykjafjall, up to about 100 metres above sea-level. Where the naked basalt does not protrude, the ground around the springs consists of greyish-white siliceous sinter almost bare of vegetation, and large tracts of it are warm and, so to speak, perforated like a sieve with numerous hot springs of all possible sizes. These appear in the form of (1) steaming holes (fumaroles) which range in size from quite fine pores to rather large funnels, (2) fountains (geysirs) which at short intervals eject boiling water ranging from quite a slender jet one foot in height to mighty columns of roaring water from 10 to 15 feet in height (Little Geysir), (3) mud-pools with bubbling, bluish-grey mud which is often ejected to a distance far beyond the surroundings of the pool, and (4) boiling basins or cauldrons which may measure 6 — 8 metres in diameter, and either have a quiet surface or boil up at short inter- vals, so that the water partially flows over the edge of the basin. The steam is everywhere impregnated with sulphuretted hydrogen, with the result that the vegetation is very poor and homogeneous. The luxuriant Sp/?are favourable here than on the stony slope, which is constantly exposed to disturbances through the down-sliding of stones and earth. The most xerophi- lous species, viz. species of Rhacomitrium and Grimmia, Dicrauo- weisia crispula, Orthotrichiim rupestre and Hypnuin revoliilnm grow on the stones, while on the ground between the stones there are favourable conditions for a number of species which have greater requirements with regard to shelter, moisture and shade. The Urd is therefore very rich in species, since lithophilous species are found there on the blocks, and species, which grow on the ground, occur between the stones, and Bryophytes belonging to heathland and grassland, are found on the soil-covered stones and ledges. In order to show how heterogeneous the composition of the Bryophyte vegetation may be, the Urd in Heljusdalur on Vest- mannaey may serve as an example. The valley is almost semicir- cular in shape, and open towards the south, and in consequence of this favourable situation combined with the comparatively mild, damp climate of the island , a considerable number of southern species are found there, while species such as Ulota maritima and Schistidium maritimum betoken the proximity of the sea. The rocks around the valley are inhabited by numerous sea-fowls, and they often rest on the blocks of the Urd, and on these spots, manured by the birds, it is species of Bryum (B. argenteum and B. capillare) which particularly make their appearance. The fallen blocks are everywhere covered with cushions of «/ mosses and liverworts. The commonest species are Schistidium apocarpum, Ulola maritima, Hypnum cupressiforme, H. uncinatum, Orthotrichiim rupestre and Ceratodon purpnreus. The following species were also observed on the blocks: Radula complanata, Ma- dotlieca Cordceana, Plagiochila asplenioidcs, Cephaloziella Hampcana, Didymodon rubellus, *Barbula cylindrica, Tortella tortuosa, T. fragilis, Tortilla subiilata , *T. miicronifolia , Distichium montanum, * Orthotri- chiim a n om a In m, Encatypta ciliata, E. rhabdocarpa , Pohlia cruda, Bryum capillare, B. elegans, B. inclinatum, B.a'ueum, Mnium serra- tum, M.stellare, M. orthorrhynchum, Myurella julacea, Orthothecium intricatum, *Isothecium myiirum, Homatothecium sericeum, Ambtyste- gium Sprucei, *A. serpens, Hypuum hamutosum and H. revolution. In the caves formed among the stones, into which the light penetrated but scantily, the walls were covered with light-green shining mats 600 A. HESSELBO of '• Plagiothetiiim depressum, the ground between the blocks was covered with a thick, dark-green carpet of Hypnum uncinatum, Hylocomium squarrosum, Brachythecinm salebrosum, :'Eurhynchium Stockesii, Plagiothechim Roeseanum, :Thuidium tamariscinum , T. abietinum , ]Mnium iindulatiim , Ditrichum flexicanle, Dichodontium pettueidum, '::Lophocolea cuspidata, *L. minor and Lophozia quinque- dentata. On the soil-covered grassy ledges and slopes, between the stones, grew Brachythecinm albicans, B. salebrosum (in masses), Cli- macium dendroides (in abundance), Camptothecium lutescens, Hyloco- mium proliferum, H. parietinum (sparingly) and Mnium affine (in abundance). All the species marked * are southern forms the majority of which have only been found in South Iceland. On the whole, the Urd affords favourable habitats for many species which do not thrive in more exposed localities. On a dry Urd consisting of large blocks of basalt, near Holt, in South Iceland, the following species were growing: Rhacomi- trium fascicalare , R- heterostichum , R. hypnoides, Grimmia Doniana, Schistidium apocarpum, Andrewa petrophila, Antitrichia curtipendula, Hypnum uncinatum, Hylocomium loreum, H. proliferum, H. parieti- num and Frullania Tamarisci. Almost the same species are found on larger detached blocks. On blocks of lava round about Reykjavik there grew particularly Rhacomitrium heterostichum, R. fasciculare, Andrecea petrophila, Schi- stidium apocarpum, Grimmia Doniana and Dicranoweisia crispula. On larger stones in the home-field (Tunet) near Valla nes (East Iceland) there grew Pterigynandrum filiforme, Hypnum revolii- /H/n, Tortula ruralis and Encalypta rhabdocarpa. Some large blocks near Hafursholt in South Iceland were quite overgrown with Grimmia alpestris. On some large blocks of basalt near Selj a land there grew Grimmia Doniana, Rhacomitrium fasciculare, R. hypnoides, R. sudeticum, Dicranoweisia crispula and Gymnomitrium coralloides. The Vertical Rock -belts. Owing to the division into layers peculiar to the basalt, the mountain sides consist of numerous vertical scarps of varying height, alternating with slopes formed by fallen blocks and debris. As a rule, the first 100 — 200 metres of the mountain form a slope which is only slightly inclined at the bottom and becomes steeper higher up, and where only here and there small portions of the primitive rock protrude. This slope is limited by a precipitous rock-face of very varying height, sometimes ris- THK BRYOPHYTA OF ICKLAM) 601 ing to a height of several hundred metres, right up lo the plateau on the mountain top, but usually divided inlo numerous steps, consisting of shelves or ledges of varying breadth. The rock-face is here and there intersected by dee}) fissures and clefts, excavated by the down ward -flowing water, which partly drains away in Fig. 29. Face of basalt rock (E. Iceland). Everywhere in the crevices small, black, moss- cushions (Andrecea. l)icntiwn>cini(i i-rispula and (irinunid spp.). these channels, partly spreads over the ledges and from thence flows down the rock-faces or penetrates into the crevices of the rock, and then reappears once more further down. Consequently, the conditions pertaining to moisture vary greatly, and therefore the moss-covering also. As some examples will best show the com- position of the latter, the following are given: 1. Esja, low damp rock- face just above the slope: The Botany of Iceland. Vol.1, part. II. 39 602 A. HESSELIJO Philonotis tomentella, Mnium punctalnm, M. orthorrhynchiim, Amphi- dium Mougeottii, A. lapponicum, Ana'ctangium compactum, Didymodon rnbellus and Schistidium gracile grew abundantly in extensive cushions. Lescnrcea filamentosa was found abundantly at the basal part of the rock-face. Pohlia cruda, Barlramia itgphylla, Plagiothednm pul- chellum, Mijnrella jnlacea, M. tenerrima, Radnla complanata, Haplozia atrovirens and Marchantia polymorpha grew partly in small tufts, partly intermixed with other species in the tufts formed by them. 2. Botnsdalur, H valfj ordur: damp rock -face. The base of the rock-face, up to a height of about a few metres, was covered with extensive cushions of Hypnum cupressiforme, H. mollnscum, Brachythecium glareosum, Orthothednm chryseum, Philonotis tomen- tella and Distichium montanum. Where the rock-face was wet with the downward-oozing water, large patches of it were covered with Anomobryum continuum. Partly in the crevices of the rock-face, partly scattered in the tufts there occurred Amblysteginm Sprncei, Brynm pallescens, B. indinatiim, Lophozia quinquedentata, L. M Ciller i, Blepharostoma trichophyllum and Aneura pinguis. 3. B e r u f j 6 r d u r, r o c k - f a c e, w here the water was oozing down from the ledge above: Hijpmim alpestre, Orthothednm chryseum, Blindia acnta, Onchophorns Wahlenbergii, Plagiopns (Ederi, Philonotis fontana, Distichium montannm, Mijnrella jnlaceci, M. tener- rima, Scapania snbalpina, Lophozia quinquedentata, Haplozia alrovi- rens and H. cordifolia. 4. Seydisfj ordur, dry rock face with a northern ex- posure. On the dry rock face itself there grew: Plerigynandrnm /ili forme, Homalothednm sericenm , Grimmia fnnalis, G. torqnata, Hypnnm revolntnm and Ortholricham rnpestre. The basal part of the rock-face was much weathered, presenting numerous crevices and small ledges. There grew: Hypnnm reuolnlnm , H. filidnum, Orthothednm chryseum, Plagiothedum pnlchellnm, P. Roeseauum, Mijnrella jnlacea, M. tenerrima, Amphidium Mougeottii, Mnium orthor- rlujnchnm, Bartramia ityphylla, Pohlia cruda, Plagiobryum Zierii, Meesea Iridwides, Orthotrichnm Blyttii, Distichium montanum, Di- trichnm flexicanle, Fissidens osmundoides, Schistidium confertnm, Didymodon rnbellns, Metzgeria fnrcata, Blepharostoma trichophyllum and Odontoschisma elongatnm. r>. Akureyri, dry rock-face, 350 metres above sea- level. The rock-face was covered with extensive mats of Homalo- thednm sericenm and Plerigynandrnm fill for me mixed with cus- THE IJIU'OPHYTA OF ICELAND hions of Grimmia funalis, Hypnum revolutum, Rhacomitrium hete- rostichum and Orthotrichum rupeslre. On the basal and somewhat damper portion of the rock-face there grew Gymnoslomum rnpestre, Philonotis tomentella, Orthothecium chryseum, Hypnum uncinatum, Distichium montannm, Ditrichum flexicaule, Amphidium lapponicum, Pohlia cruda, Bartramia itgphylla, Ceratodon purpurciis, Tortclla tor- Fig. 30. Grimmia torquata on one of the sides of Flokastadagil. tuosa, Lophozia quinquedcntata, L. quadriloba and everywhere on the ledges large cushions of fruiting Tortula rnralis. The two last quoted examples are typical of the vegetation of dry rock-faces. Homalotheciiim sericeum occurs there almost always. */ */ / and is often dominant on exposed rock-faces as far upwards as 400— 500 metres above sea-level, Pterigynandrum is also extremely common, especially in the low land. Grimmia fnnalis is rarely ab- sent and often forms very large and deep, fruiting tufts, and espe- cially in South Iceland G. torquata is exlremely common and often covers large portions of the rock-faces with its irregularly-rounded cushions (Fig. 30). 6. Low, much weathered and fissured basalt rocks near Hof in SE. Iceland. On the top of the rocks it was espe- 39* 604 A. HESSELBO cially Rhacomitrinm hypnoides which grew abundantly on debris pro- duced by disintegration. On the rocks there grew Hypnum cnpressi- forme, H. revolution, H. imponens, Pterigynandrnm filiforme, Leskea ner- uosa, Rhacomitrinm fasciculare^R. heterostichum, Grimmia funalis, G.Do- niana, Schistidium apocarpum, S. confertum , Dicranoweisia crispula, Andrecea petrophila, Orthotrichum rupestre, O. Sturmii, Gymnomitrium coralhides, Frullania Tamarisci, Radula complanata, Metzgeria furcata and at the base of the rock, Madotheca Cordccana. A southern rock- face was covered with Leiicodon scinroides var. morensis. In clefts and crevices and on soil-covered ledges there grew Mnium orthor- rhynchum, M.stellare, Pohlia cruda, Encalypta ciliata, E. rhabdo- carpa, Bartramia ityphylla, Dicranum Andersonii, Distichinm monta- nnm, Ditrichnm flexicaule, Didymodon rubellns, Amphidium tapponi- cum, Plagiochila asplenioides , Marsupella Fnnckii and Lophozia al- pestris. The locality just described comes nearest to that knowrn in Iceland as CkHolt", z. e. low, stony ridges or protruding masses of rock in the low land. The vegetation upon these "Holts" is gene- rally xerophilous in character and is, as a rule, not so rich in species as is the vegetation mentioned above. The ridges are usu- ally more or less covered with soil which bears heath-vegetation, or are occupied by gravelly flats, therefore the Bryophyte vegetation consists chiefly of species belonging to heathland or grassland (Hy- locominm spp., Polylrichnm alpinnm, P. juniperinum, P. pilosum, Hyp- num nncinatiim, Frnllania Tamarisci, Rhacomitrinm spp., etc.), while directly upon the rocks there grow species such as Hypnum cu- pressiforme, H. hamulosum, H. revolutum, Orthotrichum and Grimmia spp., and in the crevices Bartramia, Pohlia cruda, Amphidium tap- ponicum, Mnium orthorrhynchum, Myurella, Distichium montanum and other of the species found in rock-clefts in greater or smaller quantities. The Bryophyte Vegetation of the Tuff Rocks. The reason why the Bryophyte vegetation of the tuff rocks is here treated in a separate section is that the life-conditions of the plants are essentially different on a basalt and on a tuff substratum. Tuff consists of consolidated fine-grained material (volcanic ash and dust) through which are scattered larger and smaller blocks of rock. While the basalt has a smooth surface, with fissures and de- pressions only here and there, the surface of the tuff is uneven and THE BRYOPHYTA OF ICELAND rough, and therefore offers more favourable conditions to the mosses for attaching themselves to it. When a basalt and a tuff surface occur side by side, as is often the case, the difference is very obvious. Mosses grow more scantily on basalt, since it is distinctly seen that the majority of the tufts are situated in, or proceed from, Fig. 31. Tuff cleft (Blciksagil) near Barkarslaclr. a fissure, while tuff surfaces are often covered with a continuous moss-carpet, composed of many different species. It is also a fact of great importance that the water which flows down from above, and atmospheric humidity, are available to the mosses of basalt surfaces only as long as the water is flowing or is deposited, while the tuff is able to absorb water through its porose surface, and thus has a constant supply of necessary moisture for the vegetation. Owing to the slight power of resistance of the tuff against the ero- 60(5 A. HESSELBO Fig. 32. Side of lull-cleft near Barkarstadr. At Ihe loot of the cleft, among others Mniiini nndnlalitni grew abundantly. On the sides there grew Htjpnnm filicinum (at the top, to the right), Fegalclld conica (in the middle and to the left), Philonolis fonlana, Radula compla- nata, Metzneria fnrcata and Marchantia pohjmorpha. At the base of the rock-side grew, among others, Mninin nndiilatuin and Thni- dinm tamariscinum. At the extreme end of the cleft, where the sun could shine on the rock faces, fruiting specimens of Preissia commu- tata often grew7 in abundance. The walls in the numerous caves were often covered with Eiirhyiichinin Sivartzii and Fegatella conica, in company with many, or a few, of the species found on the sides Of the cleft, which, however, on the whole, did not thrive well in the scanty light. In many places Feyalella formed also a belt along the basal part of the rock-sides, especially where they projected. On the roof of the caves Blepharostoma trichophyllnm and Ambly- 608 A. HESSKLBO stecjium Sprucei formed thin, dark-green coverings, and where the water flowed down the roof and walls Thamnium alopecunim oc- curred as pure growths. A similar vegetation was found everywhere in clefts and caves, and where the conditions pertaining to light and moisture were more varying, the number of the species was still greater than in the vegetation described above. This was for instance the case in the deep and broad Flokastadagil near Breidabolstadr. There, on the damp walls, almost the same species were growing as in Fig. 33. Brijn.vipliinin norvccjicum on one of the sides of Flokastadagil. Bleiksagil. A high, dry, perpendicular rock-face was for a consi- derable distance entirely covered with a shining, dark-green mat of Bryoxiphium norvegicum (Fig. 33), which has hardly been found elsewhere in such enormous quantities. In other places Grimmia lorqnata covered the rock-sides and blocks with its irregularly-rounded cushions, and Hypnnm palustre was very common everywhere at the water's edge. Neckera complanata was common in dry ditches. At the side of a small waterfall, Klitnafoss, there was a rather large cave, down one side of which some of the water from the waterfall was running. There Thamnium alopecunim grew abun- dantly, while the drier walls of the cave were covered with Enrhyn- chinm Swarliii and Mnium orthorrhynchum. On the ground at the THE BKYOPHYTA OF ICELAND 609 bottom of the cave there grew Timmia austriaca, Brijiuu ventricosum, Brachythecium rimilare, Tluiidinm delicatulum and Marchantia poly- inorpha, and at the entrance to the cave where the water was drip- ping down, il//?w/» undulatum occurred. The upper part of the walls and the roof were covered with Blepharostoma trichophyllum, Amblystegium Sprucei, Metzgeria fnrcata and Radnla complanata, and in the better-lighted part around the entrance, the cave was covered with Homalothecium sericeum and Orthothecium intricatum. The Southern Slope of Eyjafjall consists partly of basalt and partly of tuff-layers. The numerous rivers which issue from the Jokull usually ilow at the bottom of deep, narrow clefts in the tuff-layers. v' Holtsa, which is a glacier-river of rather considerable size, flows for almost its entire course, from the Jokull down to the low land, at the bottom of deep clefts which are accessible only in a few places, the water usually rising from the bottom up to the perpendicular rock-wall. The sides are, as a rule, rather damp, and the water from the slopes above often flows down the rock- faces. The Bryophyte vegetation is extremely luxuriant, and the sides of the clefts are, for considerable distances, covered with enor- mous carpets of mosses and liverworts. The following species covered the fallen blocks and debris at the base of the cleft-sides : Hylocomium spp. f especially H. sqnarrosuin and H. proliferum) , Hyp- nnm stellatum, Acrocladiam cuspidatum, Climacium dendroides, Eu- rhynchium Stockesii, Thuidium tamariscinum, Mniiun undiilatum, M. pnnctatum, Timmia austriaca, Marchantia polymorpha, etc. In the numerous open caves and under overhanging rocks, a characteristic vegetation of Marchantiacece was found. Preissia commntata (fr.) and Fegatella conica covered the sides with metre-broad mats, and Re- boulia hemisphcerica occurred abundantly in several places, and was also_fruiling. Here Enrhijnchiiun Swarlzii also was at home, espe- cially on the less damp rock-faces, while Thamnium alopecurum preferred spots where the water was flowing down. Where stream- lets were running from above down the rock-sides, there grew Rhynchostegium rusciforme, Brachythecium rivulare, Haplozia cordi- folia and, lowermost, Thamnium, while the more or less damp rock- laces were covered with a variegated carpet of mosses and liver- worts, unusually rich in species and composed of Hypiuun filicinum (in masses), H. falcatnm (in masses), H. molluscum (in masses), Philo- notis tomentella, P. fontana (in abundance), Mninm serratum, M. stel- (310 A. HESSELHO tare, M. orthorrhynchnm, Brynm ceneum, B. inclinatnm, B. pallescens, B. ventricosum, Mniobrynm albicans (common), Pohlia crnda, Plagio- brynm Zierii, Anomobryum fill forme (in one place in fr.), Amphidium Mougeottii, A. lapponicnm, Anccctangium compaclum, Hymenostylium curvirostre, Blindia acuta, Ditrichum flexicaule, Distichium montannm, Barbula cylindrica, Didymodon rnbelhis, Tortella toriuosa, T. frag His, Grimmia apocarpa, Myurella jnlacea, Haplozia riparia, H. atrovirens, Madotheca Cordcearia, Lcjcnnea serpyllifolia, Radnla complanata, Met:- geria fnrcata, Chiloscyphns polyanthus, Lophocolea cuspidata (scanty). Scapania irrigna, Lophozia qninqnedentata, L. M filler i and Anenra pingnis. The moss- carpet covering dry rock-faces and large blocks was chiefly composed of Hylocomium loreum (also in fr.), H. proli- fernm, Hijpnum uncinatum, H. hamulosiim and H. callichronm. In a dry cave above the cleft there grew Neckera complanata, Brachythe- cinm popnleiim, B. velutinum, Plagiothecium denticnlatnm, P. depressnm, Isothecmm tenuinerue, Mnium cuspidatum, and on the roof of the cave there grew Amblystegium Sprncei and Blepharostoma. The southern side of Drangshlidarfj all and the small neigh- bouring group of mountains, Hrutafjall (Fig. 34), consist, in a great measure, of dry, lofty faces of tuff-rock, as much as 200 metres high, the base of which is moss-grown. One of the commonest species here is Leucodon sciuroides var. morensis which covered the rock-face for a considerable distance upwards with its extensive and often richly-fruiting mats. The following species were also com- mon : Homalotliecinni sericeum, Pterigynandrum filiforme, Hypnani revolutnm and Grimmia torquata. At the foot of the rock-faces there grew Isothecmm mynriim (in abundance), Orthotrichum rupestre, Didymodon riibellus, Barbnla cylindrica, Brynm capillare, Tortella tortnosa, Encalypta cillata, Neckera complanata, Myurella jnlacea and Metzgeria furcata, and where the water was oozing through cracks and crevices the rock-face was covered with Blindia acnta inter- mixed with Hypnnm mollnscnm , H. palnstre and the rare Anomo- brynm concinnalnm. Among the large blocks of tutT on a small Urd there grew, among others, Mnium iindnlalum, Enrhynchinm pilifernm, Hhyncho- stegium murale (abundantly), Amblystegium Juraizkamim , Leskea neruosa and Lejennea cavi folia. The walls in the interior of a ralher dry, open cave, were covered with Preissia commntata, Fegatella conica, Marchanlia poly- morpha, Distichium montanum, Bryoxiphinm noruegicum,Ancectangium THE BRYOPHYTA OF ICELAND compactnm (all in abundance), Reboulia hemisphcerica , Mniuin or- thorrhynchum, Fanaria hygrometrica, Bnjnm ccneum, B. inclinatuni, Orthothccium intricatum, Blepharostoma trichophyUiim and, where it was somewhat damper, with Eurhynchium Swartzii. Fig. 34. Hriitafell south of Eyjafjallajokull. Tlie perpendicular face of tuff-rock in the centre, is about 200 metres high, and, at the foot is covered with extensive moss carpets, whilst caves occur in many places. A very interesting kind of vegetation was found on the dry */ c.* *.} *, faces of a small isolated rock, Drangshellir. There grew Leiicodon sciuroides var. morensis, Homalothecium sericenin, Leskea nervosa, Grimmia Doniana, Barbnla mnralis, B. obtusifolia, Orthotrichum ano- malum and 0. rupestre. Half of these species consist of xerophi- lous southern forms, which have their northern limit in South Ice- land, and are there met with only in specially protected localities. Drangshlid, which has a height of 478 metres, protects this locality 612 A. HESSELBO from the cold, north winds, without, however, preventing the sun from warming the tuff-faces. The Bryophyte Vegetation of the Lava-fields. A very great part of Iceland is covered with lava. According to Thoroddsen (1914, p. 219) the post-glacial lava-fields of Iceland cover an area of about 11,200 square km. or almost Vs of the entire area of the island. It is, however, only a very small part of this vast area which has been an object of bryological investigation. Gronlund (1874, p. 136 and 1890) was the first to mention the vegetation of the lava-fields, in his description of the Rhacomitriuiu heath as important for the further development of the plant covering. Ostenfeld (1898, p. 246) has given a description of the lava-fields of the peninsula of Reykjanes without, however, entering more closely into the subject of the Bryophyle vegetation. Helgi Jonsson (1900, p. 89) has given a very detailed account of the vegetation of Budahraun and Eldhraun in West Iceland, also with regard to the Bryophyta, and the same author, in his description of the vegetation of South Iceland, mentions the Bryophyte vegetation of several lava- fields, especially modern ones. Lastly, A. Wegener in 1912 made a few collections on the high-lying Odadahraun (600 — 1200 metres above sea-level). Besides a small part of Myvatnshraun, around the farm Rey- kjahlid, which was very superficially investigated owing to the inclemency of the weather, my own investigations include only the lava-fields o£ SW. Iceland, especially Hafnarfjardarrhraun, Thingvalla- hraun and Svinahraun around Kolvidarhol. The lava-field is no single formation, but, on the contrary, in- cludes a great number of different formations, ranging from the dry rock-flats, and the Rhacomitrium heath, through the heather moor and grassland to the bog formations in the deepest hollows, and the associations of damp rocks in clefts. When it is nevertheless described here in a separate section, as by Helgi Jonsson, the reason is that the vegetation of the lava-fields of the lowlands every- where presents so many common features and peculiarities that we may be justified in describing the Bryophyte vegetation occurring there. According to the nature of the surface, the lava-fields may be classified into two groups, viz. block-lava (Icelandic Apalhrann) and sheet-lava (Icelandic Helluhrann). The former consists of blocks of THE BRYOPHYTA OF ICELAND 613 lava thrown together into irregular heaps, while sheet-lava consists of large, irregularly broken surfaces, which are formed by a process of slow solidification, and are furrowed by innumerable clefts and fissures, both narrow and broad. Here vesicular hollows are also found, produced by the moisture of the substratum which has formed large steam-vesicles in the molten lava, and after solidification the Fig. 35. Lava-field in the district of Borgarfjordur. The lava is covered to a depth of one foot with a layer of Rhacomitrinm hypnoides. Projecting parts of the lava are covered with crustaceous lichens. Here and there a tuft of Festucu oinna. Birch coppice in the background. roof of the vesicle has collapsed, and has formed a platform on the floor of the cavity. Such vesicles in the lava which are characterized by very luxuriant vegetation, since they afford excellent shelter for the plants, and are inaccessible to sheep may differ rather greatly in depth, according to the thickness of the lava-sheet. In Budahraun, according to Jo us son, their depth averages from 2 — 6 metres, but is usually somewhat above 2 metres, and in Hafnarfjardarrhraun the depth was also usually some 2 metres. The lava-fields are often furrowed by deep clefts or cracks, frequently of considerable length and with perpendicular sides. This is, for instance, the case in Thingvallahraun where the best-known cleft, Almannagja, has a length of almost 15 kilometres. 614 A. HESSELBO The surface of the lava-field is very dry, because the water can easilv drain away through the cracks, therefore, the vegetation there «/ «/ • U 7 is decidedly xerophilons. As a rule, the Rhacomitrium heath (R. hypnoides) in which other Bryophyta, such as Dicranuin sco- parium, Hijlocomium proliferum and Ptilidium ciliare, occur only extremely scantily covers the greater part of the lava-fields, and there arrives at its fullest development, so that extensive areas may be found covered with foot-deep, soft, greyish carpets which hide all irregularities of the surface. The importance of the moss-covering for the further development of the plant-covering, partly by binding the drifting sand, partly by forming soil, has been demonstrated by Gronlund and Helgi Jonsson. The chief reason for the extensive distribution of the moss-heath must undoubtedly be sought in the nature of the surface. This is, as a rule, highly vesicular, and contains numerous small holes and cavities, in which the plants find good conditions for taking root. Therefore, many of these cavities are filled up with small moss- cushions (Fig. 36), which, from thence, extend over the rock-surfaces and gradually merge into one another (Helgi Jonsson, 1900, p. 83). The tops of the lava-cones and the protruding blocks are not covered with a continuous moss-carpet, but usually with scattered cushions of mosses, liverworts and lichens. The most frequent species there are Rhacomitrium heterostichum, R. fascicnlare, Grimmia apocarpa, G. funalis, Andrecea petrophila, Hypnum reuolntnm, Ho- malothecium sericeum, Pterigynandrum filiforme, Dicranoweisia cris- pula, and occasionally Gymnomitrium coralloides, G. concinnatnm, Dicranum fulvellum, Rhacomitrium siideticum, Potutrichum pilosum, besides which there are several other species. Thus, near Hafnar- fjordur (and partly also in Budahraun), in addition to the majority of the species mentioned above, there occurred Orthotrichum rupestre, 0. Sturmii, Grimmia patens, Leucodon sciuroides var. morensis, Isothe- cium tenuinerue and FrnUania Tamarisci. Near Thingvellir, where the surface of the lava is very dry, there grew upon the lava-cones many crustaceous lichens, Rhacomitrium fasciculare (in abundance), Grimmia apocarpa, Andrea>a petrophila, Potijtrichum pilosum and, here and there, some Gymnomitrium coralloides and Dicranum ful- vellum; and, where some soil had accumulated, Ceratodon purpureus and Pohlia nutans grew scantily. In the depressions Rhacomitrium hypnoides was gradually replaced by R. canescens, heather moor and grassland, and in the deepest depressions small patches of bog and THE BRYOPHYTA OF ICELAND 615 swamp vegetation may occur. The Rhacomitrium heaths are gra- dually transformed into heather moors and birch coppices through the decaying of the mosses and their forming humus. But all these Fig. 36. The surface of a lava block with small moss-cushions (Andrcira. Grinnnict spp. and Gymnomitrium coralloides). formations will not be treated of more fully here as the mosses occurring in them have been mentioned in previous sections. Very extensively distributed and very characteristic is the Rhacomitrium- canescens formation which often replaces R. hypnoides in flat depres- sions where the ground is somewhat damp, and where some sand has accumulated. It is often abundantly mixed with other Bryophyta such as Hylocomium spp., Hypniun nncinatiim, Dicranum scoparium, Polytrichum alpinum and species of Lophozia. 616 A. HESSELBO Lava-clefts. The caves, clefts and cavities which occur every- b where in the lava-fields contain a Bryophyte vegetation very rich in species. In the broader clefts and in the lava-vesicles (Helgi Jonsson's "Herb-cavities", 1900, p. 90) the bottom is often covered Fig. 37. Lava-cleft near Thingvellir (Almannagj;'\). The lava-blocks are quite covered with Rhacomitrium hypnoides. with ferns and flowering plants, and especially in deeper clefts, or where the bottom is covered with loose blocks, there is also found a continuous carpet of mosses and liverworts in which Hylocominm spp. (H. proliferum , H. parietinuin , H.loreum, H. squarrosum and H. triquetrum) together with species of Rhacon\itrium, Hijpnnm and Dicranum play a prominent part, and are usually much interwoven with liverworts such as Lophozia lycopodioides, L. quinqnedentata, L. Kunzeana, Cephalozia spp., Alicularia scalaris, Ptilidium ciliare, etc. THE BRYOPHYTA OF ICELAND 617 Very frequently a large form of Hypnnm callichroum, with regularly two-rowed ramification, is the most abundant constituent of the vegetation, especially in somewhat damp and shady clefts. Eurhyn- chium pilifernm is often met with very abundantly, especially where Fig. 38. Lava-cleft near Thingvellir. At the bottom there is a very luxuriant vegetation of ferns, Geranium silvuticum, etc., and in the crevices large moss-cushions occur everywhere. the bottom is grass-covered, and several other southern forms, for instance Eurhynchium Slockesii and Isothecium myiirum, likewise have a preference for the sheltered lava-clefts. In the very deep lava-clefts the conditions are somewhat dif- ferent from the aforesaid. Where the cleft is broad enough to allow the sun to shine on the bottom during a part of the day, a luxuriant covering of ferns, flowering plants or mosses is found (Fig. 38); but where the cleft is so narrow that the light is strongly subdued, the The Botany of Iceland. Vol. I, part 11. 40 618 A. HESSELBO higher plants and the Hylocomium mats do not thrive. The snow lies here till far into the summer, and in many cases the tempera- ture hardly ever rises above freezing point. The bottom of these clefts is therefore either quite bare of vegetation, or covered only with mosses. At the bottom of narrow clefts (15—20 metres or more in depth) near Thingvellir, where snow and ice were still to be found even at the end of July, Anthelieta occurred on a damp sub- stratum as they do on flats irrigated by melting snow on mountain heights. Polytrichum sexangulare and Pohlia commutata grew abund- antly here as on rocky flats. The plants were considerably higher and more slender than on the rocky flats,, and only slightly tomen- tose. The same was the case with Conostomum boreale and Mniobryum albicans, which likewise occurred in several clefts. The Bryophyte vegetation occurring there is affected both by the low temperature and also the deficient light and total absence of wind, which all combined contribute to produce a stronger longitudinal growth and a slighter development of rhizoids. Several other species, which have their main distribution on mountain heights, and are rare in or quite absent from the lowlands, are widely distributed about the lava-fields. In almost all the lava -fields of South-west Iceland, Pleuroclada albescens var. islandica, Dicranum molle, D. Blyttii and D. Starckei are commonlv found in clefts, not onlv in those that \, */ are narrow, but especially in the broad moss-grown clefts, where Dicranum spp. form large tufts on the blocks of lava. On the sides of the clefts and of the fallen blocks, a great many mosses grow. Diplophyllum albicans is a character-plant of the lava-fields of SW. and W. Iceland; it is extremely common there, but is very rare and scanty in other localities. On the vertical, dry sides of clefts the mosses usually grow in large rounded cushions. The commonest species are Tortella tortuosa, Anoectangium com- pactum, Amphidium Moiigeottii, Grimmia torquata and G. funalis, but many other of the species occurring on rocks and on the ground are always found both on the walls and also on, and among, the blocks. The Bryophyte vegetation of lava-clefts has the greatest resemblance to that found on the Urd, but some of the most light- loving species are absent, for instance Orthotrichum, several Grimmia and Rhacomitrium spp. and Dicranoweisia crispula, while, on the other hand, others are found which belong to damp clefts or which need more shelter. Mesophilous forms are in the majority, whilst hygrophilous forms are, as a rule, entirely absent. THE BRYOPHYTA OF ICELAND 619 In the following pages some examples of the Bryophyte vege- tation of lava-clefts will be described. Thing vail a lira un. The lava-clefts (Icelandic Gja) there, are peculiar on account of their unusual depth (as much as 20 — 30 metres). Several of those situated nearest to the lake of Thingvellir have deep water at the bottom. The Bryophyte carpet at the bottom of the clefts is composed of Hylocomhun loreum, H. proliferum, H. parietinum, H. sqimrrosum, Hypniim uncinatum, H. callichroum, H. stramineum, H. molluscum, Eurhynchium piliferum, Antitrichia curtipendula, Polytrichum alpinum, Rhacomitriiim hypnoides, R. canescens, Dicranum Blyttii, D. Starckei, D. mollc, Sphagnum teres, S. Girgensohnii, Lophozia uentricosa, L. quinquedentata, L. Knnzeana, L. alpestris, Ptilidium ciliare and Sca- pania irrigua. On the sides of the clefts there grew especially An- cectangium compactum, Grimmia torquata, G. funalis, Gymnostomum rupestre, Amphidium Mougeottii and A. lapponicum. Intermixed with these, and in cushions on the ledges, in the crevices and among the blocks there grew: Hypniim cupressiforme, Isoihediim tenuinerve, Ptagiothecium pulchellum, P. denticulatum, P. silvaticum, Amblystegium Sprucei, Neckera complanata, Schistidium gracile, Rhacomitriiim sude- ticum, Scelania ccesia, Ditrichum flexicaule, Tortella tortuosa, Fissidens osmundoides, F. bryoides (rare), Pohlia cruda, P. commutata, Bartramia ityphylla, Conostomum boreale, Philonotis tomentella, Mnium orthor- rhynchum, Bryum pallens, Plagiobryum Zierii, Distichium montanum. Diplophylhun albicans (in abundance), Lophozia heterocolpos, Lejennea cavifolia, Blepharostoma trichophyllum, Alicularia scalaris, A. geo- scypha, Anthelia Juratzkana, Scapania subalpina, Pleuroclada albescens var. islandica, Cephalozia bicuspidata, Eucalyx siibcllipticus, Gymno- mitrium concinnatum, Metzgeria furcata, Radula complanata, Aneura pingnis and Preissia commutata. The above list is very long, but is nevertheless hardly complete, since some of the common chomophytes are not enumerated in itr and, at any rale, several of them were undoubtedly forgotten, while the list was being made on the spot, but it gives a good idea of the exceedingly great number of species which are found in these localities. H afn a r fj arda rhraun. Almost the same species are found there as in Thingvaiiahraun, but the situation close to the sea-side makes its influence felt. Rhacomitriiim heterostichum and R. fasci- culare are exceedingly common, and in several places Ulota maritima 40* 620 A. HESSELBO occurs on lava-blocks and Trichostomnm littorale on the sides of the clefts. Scapania dentata was frequent on the ground at the bottom of shady, damp clefts. Reboulia hemisphcerica and Frullania fragili- folia were found in a single spot on the walls of caves. On the ground at the bottom of deep, dark caves, shade-forms are often found, especially of Hepaticce, with greatly elongated shoots and expanded, widely scattered leaves. Here, it was especially the following species which were common : Cephalozia bicuspidata, Pleuro- clada albescens var. islandica, Alicularia scalaris and Blepharostoma trichophyllam, occasionally also Preissia commutata and in a single spot Ditrichum homomallum and Oligotrichum hercynicum. Svinahraun is situated about 30 km. south-east of Reykjavik, and about 250 — 300 metres above sea-level. The part which has been investigated is situated in the neighbourhood of the farm Kol- vidarhol, and is of block-lava consisting of blocks and flags piled up into wild-looking heaps, some 10 metres high, with numerous clefts and caves. The top part is covered with an unusually thick and luxuriant mat of Rhacomitrinm hypnoidcs from which other mosses and flowering plants are almost absent. On the walls there grew Amphidium Mougeottii, Tortella tortuosa and Anoectanginm com- pactum. In caves and clefts there wras a Bryophyte carpet consisting of Hypnum uncinatum, H. callichroum, Hylocomium loreum, H. proli- ferum, H. parietinum, Lophozia quinquedentata, L. lycopodioides, L. Floprckei, Plagiochila asplenioides and Ptilidium ciliare. DiplophyUum albicans was extremely common everywhere. In addition to the above the following wrere found more or less abundantly: Polytrichum alpinum, Diphyscinm sessile, Bartramia ityphylla, Conostomnm boreale, Mnium orthorrhynchum, Pohlia cruda, P. commutata, Mniobryum albi- cans, Brymn elegans, Amphidium lapponicum, Rhacomitrium sudeticum, Schistidium gracile, Fissidens osmuudoides, Dicranum scoparium, Di- stichium montanum, Sphagnum teres, Lophozia alpestris, L. quadriloba, Alicularia scalaris, Anthelia Juratzkana and Blepharostoma tricho- phyllum. It will be seen that the lava-fields here described greatly re- semble each other, and that it is essentially the same species which constitute the bulk of the vegetation in all of them. Svinahraun is situated on the ridge of hills which extends along the whole length of the peninsula of Reykjanes, and the climate there is ex- tremely cold and damp, which is proved by the fact that it is the Rhacomitrium heath which forms the last stage in the development THE BRYOPHYTA OF ICELAND 621 of the vegetation of the flats, and that many of the species of the low land are absent. Unfortunately there was no opportunity of investigating the lava-fields of West Iceland more closely, since unfavourable atmos- pheric conditions with rain and fog, combined with a want of time, made a longer stay there impossible, but the conditions appear to be essentiallv the same as in South-west Iceland. I, In his description of Budahraun Helgi Jonsson has also men- tioned some mosses, and, as far as is possible to judge from the lists which, however, are no doubt incomplete, the conditions there are exactly like those in Hafnarfjardarhraun. There also coastal species are found, for instance Ulota maritima, and southern species such as Eurhynchium Stockesii and Lejeunea cavifolia, and the dominant species are quite similar to those in the lava-fields of South-west Iceland. In North Iceland the Bryophyte vegetation of the lava-fields has an essentially different composition from that in West and South- west Iceland. All the lava-fields there are situated at a distance from the coast, and at a higher level above the sea, the vegetation is therefore decidedly xerophilous both on exposed surfaces and in clefts and crevices. The immense lava-flats at a great height above sea-level, are deserts almost entirely void of vegetation ; they have, however, been very little investigated. There are to hand only a few collections from Koch's tour across Odadahraun in 1912, and these consist only of Tortilla ruralis, Ceratodon purpureus and Di- cranoweisia crispiila, which grew here and there upon the lava. The onlv lava-field which has been investigated is Mvvatns- \J *J hrauii, which is about 160 years old, and upon which the farm Reykjahlid stands. It was described by Gronlund in 1890 and does not appear to have undergone any great change since that time. The Rhacomitrium heath occurred only scantily in the depressions, while the lava-cones were bare of vegetation or covered with scat- tered moss-cushions and crustaceous lichens. In the intervening space between the farm and the lake the following species were observed : Upon the blocks and on the lava were found Tortala ruralis, Ceratodon purpureus, Rhacomitrium hypnoides, Grimmia Don- iana, Schistidium confertum, Dicranoweisia crispula, Polytrichum pi- losum and Hypnnm revolutum, all of which were very common. In sandy soil, especially in depressions, there grew Desmatodon latifolius and Rhacomitrium canescens. In dark caves and clefts Lophozia 622 A. HESSELBO lycopodioides was usually the only species found and it formed there extensive mats. On the ground among the blocks and on the sides of these hlocks as also on those of broad clefts there grew Brachy- thecium reflexum, Lescurcea filamentosa, Eurhynchium diver sifolium (scantily), Polytricham alpinum, Timmia austriaca, Bartramia ityphylla, Encalypta rhabdocarpa, Bryum elegans, B. inclinatam, Schistidium apocarpum, Didymodon rubelhis and Plagiochila asplenioides. The above is a decidedly xerophilous flora from which not only all the mesophilous and hygrophilous forms from SW. Iceland, but also the lowland or southern forms proper, are entirely absent. In several places in this lava-field the heat of the substratum makes itself felt in deep caves and clefts. In a warm, damp cave where the temperature was about 25° (outside 4°-5°) there grew Fissidens osmnndoides, Plagiothecium denticulatum, Calypogeia Tri- chomanis, Plagiochila' asplenioides and Sphagnum rubellum. The development of the Bryophyte vegetation of the lava-fields has been very little investigated. The Bryophyta together with the lichens are the first plants which appear. The surface of the lava is very rough, consisting of small round cavities (lava vesicles) in which the spores find favourable conditions for germination, and form small rounded cushions which adhere very closelv to the sub- «/ fc.' stratum and, if conditions are favourable, extend over the entire surface of the lava as a continuous carpet. It is, however, only in the most exposed parts of the lava-field, that the mosses are con- fined to the vesicles; this is not the case in the clefts. Jonsson (1905, pp. 55 and 56) has given a description of Kra- katindshraun near Hekla, a lava-field about 23 years old. The mosses grew there only in tiny, scattered cushions upon the lava, without anywhere forming continuous carpets; down in the clefts they grew somewhat more abundantly. There the following species were found: Bartramia ityphylla, Pohlia cruda, P. commutata, Bryum pallens, Bryum spp., Ceratodon purpureus, Dicranoweisia crispula (the commonest species), Rhacomitrium hypnoides, R. canescens, Scapania curta and Lophozia alpestris. The further development is exceedingly slow. On the flats Rhacomitrium hypnoides will usually grow over all the species and suppress them, but the formation of a continuous Rhacomitrium heath appears to require a very long time, in many cases, centuries, and the further development of the moss-heath into heather moor, birch coppice or other formations, through the decay of the mosses and their forming soil, undoubtedly takes place even more slowly. THE BRYOPHYTA OF ICELAND 623 II. THE BRYOPHYTE VEGETATION OF MOUNTAIN HEIGHTS. In "Vegetal! onen paa Snaefellsnes" (Helgi Jonsson, 1900) the plant formations of mountain heights are classified into three groups, viz., Rocky flat, Grimmia heath and Mountain bogs. Of these the Grimmia heath (Rhacomitrium heath) has already been described in a previous section. Rocky Flat. By Rocky Flat Jonsson understands that part of the country which is situated above the upper limit of the heather moor (and the birch), with the exception of the mountain bogs and the Rha- comitrium heath. Its surface varies greatly, and consists sometimes of gravelly or clayey flats, sometimes of horizontal or sloping stony tracts, bare rocks or talus of debris, all of which, however, have one characteristic in common, viz., that higher plants do not form any continuous carpet, but grow scattered singly or in small societies in the most sheltered localities. The lower limit of the rocky flat varies greatly according to the local conditions. It generally begins at an altitude of about 300 — 400 metres, but often typical rocky-flat formations are met with at far lower levels, in NW. Iceland, for instance, as far down as to the sea-level. Bryophyta play a very prominent part in the vegetation of the rocky flat, and are often dominant there, or form special Bryophyte associations. The dry, gravelly flats are poor in plants, and are often quite devoid of vegetation. Of mosses, as a rule, only Rhacomitrium hyp- noides is met with in scattered cushions, especially around some- what large stones, where it can hold fast, and find some shelter. In somewhat damper and less exposed localities Rhacomitrium heaths are developed as in the lava-fields of the low land, but whilst the mosses in the low land gradually make room for other plant asso- ciations by accumulating the blowing sand around them, and by forming humus, this is not the case on the rocky flat. Here flowering plants occur extremely scantily in the Rhacomitrium heath, which therefore forms the final stage in the development of the plant- covering, and is not replaced by other formations. On large stones on the rocky flat there grew jet-black cushions of Andrecea petrophila, Dicranoweisia crispula, Rhacomitrium fascicu- lare, R. sudeticum and Schistidium apocarpum. 624 A. HESSELBO On somewhat damper gravelly ground, especially where large blocks lie scattered and afford shelter, the Bryophyte vegetation be- comes richer, so that here we sometimes tind a continuous carpet of mosses and liverworts, through which the tops of the stones protrude. This carpet of mosses and liverworts is usually composed of a larger or smaller number of the following species: Hylocomium proliferum, Hypnum uncinatum, Rrachythecium reflexum, Lescarcea Breidleri, Rhacomitrium hypnoides, R. fascicnlare, R. sudeticum, R. canescens, Schistidium apocarpum, S. gracile, Rryum ventricosum, Pohlia commutata, P. cucnllala, P. graciliSj Philonotis fontana, Conostomum boreale, Dicranum Blyttii, D. molle, D. Starckei, D. congestum, Poly- trichum sexangulare, Oligotrichum hercynicum, Lophozia alpestris, L. quinquedentata, L. ventricosa, L. lycopodioides, L. Floerckei, L. quadri- loba, Alicularia scalaris, A. geoscypha, Pleuroclada albescens, Anthelia Juratzkana and Gymnomitrium concinnatum besides some rare or more casual species, for instance Eiirhynchium diver si folium, Rrachy- thecium glaciate, Aulacomnium turgidum, Rryum elegans, Bartramia ityphylla, Pohlia Ludivigii, Didymodon rnbellus, D. rufus, Desmatodon latifolius, Distichium montanum, etc. Usually several species grow intermixed, but the moss carpet may also be formed by a single species or a few. At elevations above 500 — 600 metres Rhacomitrium sudeticum often forms extensive growths on gravelly flats. Flowering plants are entirely absent, but lichens (Cetraria islandica, Cladonia spp. and Stereocaulon condensatum) may occur abundantly in this moss carpet. In the more low-lying parts of the rocky flat Rha- comitrium sudeticum rarely occurs abundantly, but is replaced by Schistidium gracile and Schistidium apocarpum, which form low, blackish-brown or reddish-brown mats. Lescuraa Breidleri is a com- mon species, especially in NW. Iceland, where it is in many places the most abundant constituent of the vegetation on stony slopes. Couostomum boreale is also common, especially in NW. Iceland where, on the dry gravelly flats of the mountain heights, the inter- vening spaces between the stones are filled up with its compact tufts. Rrachythecium glaciate in company with Hypnum stramineum covered the damp areas of the rocky flat near Isafjordur, at a height of 450 — 500 metres. In the channels, in which the water is drained away during the melting of the snow, the stones are often entirely covered with Muiobryum albicaus var. glacialis, and in damp spots and near springs Phitonotis fontana forms light-green cushions, as it does near the "Dy" in the more low-lying tracts. In the following THE BRYOPHYTA OF ICELAND 625 pages some examples of the rocky-flat vegetation will be given, it is, however, only in NW., SW. and in a few districts of N. and E. Iceland, that this vegetation has been somewhat closely investigated, whilst the whole of the interior high land is quite unknown as far as bryology is concerned. 1. South Iceland. Barkarstadr, dry stony flat at an alti- tude of 350 metres: Scattered cushions of Schistidium apocarpum v. rufescens, Rhacomitrium hypnoides, R. fasciculare, Dicranoweisia cris- pula and Andrecea petrophila. 2. Gravelly flat on Esj a, at an altitude of about 550 metres: Moss carpet, partly torn up by the wind, composed of Hijpmuu uncinatiim and Schisiidium apocarpum, scattered in which occur rocky-flat plants such as Silene acaulis and Saxifraga oppositi folia. 3. Akureyri, rather dry gravelly flat, at an altitude of about 900 metres : Moss carpet composed of Rhacomitrium hypnoides, Hyp- num uncinatum, Hylocomium proliferum, Camptothecium nitens, Aula- comnium turgidum, Dicranum congestum, Didymodon rufus, Eurhyn- chium diuersifolium , Lophozia quinquedentata and L. quadriloba. Flowering plants entirely absent. On a dry slope at an elevation of about 770 metres there grew Lescuraea Breidleri, Brachythecium glacials, B. reflexum, Dicranum Starckei, Lophozia lycopodioides and L. alpestris, and on damp gravelly flats near the snow line there grew Pohlia gracilis (abundantly), P. cuciillata, P. commutata, Poly- trichum sexangulare, Oncophorus virens, Dicranum Starckei, Lophozia alpestris, L. uentricosa, L. quinquedentata, L. quadriloba, Pleuroclada albescens and Anthelia Juratzkana. Salix herbacea-Sibbaldia Vegetation (Helgi Jonsson, 1900, p. 33) occurs everywhere in damp depressions and on slopes where the subsoil consists of a layer of clay. This vegetation has its main distribution from 300 — 400 metres to about 700 metres, and here, close to the snow line, it is replaced by pure moss-com- munities, in which Salix herbacea occurs but scantily and at last disappears entirely. The moss community consists of a low, dense carpet of mosses and liverworts, interwoven with creeping stems of Salix herbacea, so that only the tips of the shoots protrude above the carpet. The most abundant constituent of this moss carpet is usually a low-growing form of Hypnum uncinatum or of Dicranum Starckei in association with Rhacomitrium canescens, Dicranum molle, Conostomum boreale, Potytrichum sexangulare, Anthelia Juratzkana, Pleuroclada albescens, species of Lophozia, and sometimes other species. 626 A. HESSELBO Anthelia flats (Helgi Jonsson, 1900). In damp parts of the rocky flat, especially where the snow-water from the melting snow- flats spreads out over the ground, extensive flats of a greyish-black or bluish-black colour are very commonly met with, and these are •/ u principally formed of Anthelia Juratzkana. Interspersed in this Anthelietum occur several other Bryophyta of which the most frequent are Alicalaria scalaris, A. geoscypha and Lophozia alpestris, while scattered plants of Polytrichum sexangulare, Oligotrichiim her- cynicum and Pohlia gradlis protrude here and there. Pleuroclada albescens is also occasionally met with. Although the Anthelia vegetation also occurs in more low-lying tracts, yet it has its main distribution near the snow line, and must therefore be reckoned to the moss associations of the Snow region. There are only a few Bryophyta which occur in the Snow region. At the boundary between the Anthelia-ftais and the drier gravelly flats Dicrannm falcatum occurs in semiglobular cushions, densely matted with rhizoids, but it lies so loosely upon the gravel that one can lift up the whole cushion. Near Dyrafjordur Gymnomitrium varians grew in a similar manner to Anthelia, close to the melting snow-flats. Dicranum Starckei, D. Blyttii, Pohlia cuciillata, P. com- mutata, Oligotrichiim hercynicum and Polytrichum sexangnlare are also common near the snow line but, with the exception of a few species (Dicranoweisia, Andre&a and Rhacomitrium spp.) growing on rocks, the list is thereby exhausted. Mountain Bogs are extensively distributed in great parts of Iceland, but have not yet been more closely investigated. The vegetation in the boggy depressions often consists of a low, black mat of Hypnacew, mostly Hypnum revolvens, H. exannulatum, H. sarmentosum and H. strami- neum; but the moss covering may also contain other species and, in composition, somewhat resemble the bog vegetation of the low land, although the species are fewer in number. Near Akureyri boggy flats, situated 500 — 600 metres above sea-level, were partly covered with Hypneta and partly with Cin- clidium stygium with scattered cushions of Sphagnum and species of Lophozia. On a wet flat, at an altitude of about 600 metres, there grew Polytrichum commune (in abundance), Hypnnm sarmen- tosum, H. stramineiim, H. Lindbergii, H. iincinatum, Dicranum Starckei, Sphagnum teres, S. Girgensohnii, Meesea trichoides, Bryum ventricosum, THE BRYOPHYTA OF ICELAND 627 a eo Dissodon splachiioides, Dichodontinm pelhicidiim, Aongstroemia longipes and Lophozia Knnzeana. Barkarstadr (South Iceland). On a tract of knolly bog- land, 530 metres above sea-level, there grew Hypnum turgescens, H. 628 A. HESSELBO revolvens, H. exannulatum, H. Richardsonii, H. sarmentosum, H. poly- gamum, Hylocomium squarrosiim, Oncophorus Wahlenbergii, Dicho- dontium pelliicidum, Aongstrccmia longipes, Bryum ventricosum, Pohlia gracilis, Dissodon splachnoides, Dicranum congestum (in the Sphagnnm- tufts), Sphagnum teres, Alicnlaria scalaris, Scapania irrigua and An- thelia Juratzkana. Judged from a botanical point of view, the interior high land has been very superficially investigated. As regards the mosses, only a few collections are to hand, which were made by A. Wegener during Koch's tour through the island in 1912. But as regards almost all these collections, conditions pertaining to soil and height above sea-level have not been more closelv notified. \j Hvannalindir (altitude 656 metres): Hypnum stellatum, H. re- volvens, Philonotis fontana, Pohlia commutata (fr.), Distichium mon- tanum, Splachnum vasculosnm and Aongstrcemia longipes. Eyolfsfjall (June 22nd): Anlacomnium palustre, Philonotis to- mentella, Bartramia ityphylla, Bryum ventricosum, Cinclidium stygium, Timmia norvegica, Mnium affme var. integri folium, Pohlia cruda, Di- stichium montanum, Dichodontium pelliicidum, Hypnum sarmentosum, Amblystegium Sprucei and Anthelia Juratzkana. Esjufjall. Rhacomitrium canescens, R. hypnoides, Distichium montanum, Philonotis tomentella, Mnium orthorrhynchum, Pohlia cruda, Bryum spp., Hypnum iincinatum, H. reuolutum and Anthelia Juratz- kana. Wet Bogs and River banks; June 22nd (without more parti- cular specification of the locality). Hypnum exannulatum, H. Kneiffii, Anlacomnium palustre, Philonotis fontana, P. tomentella, Mniobryum albicans var. glacialis, Pohlia commutata, Distichium montanum, Schis- tidium gracile and Aongstrcemia longipes. These lists almost exclusively contain species which are of common occurrence everywhere. III. THE COMPONENTS OF THE BRYOPHYTE FLORA. IN consequence of the geographical situation and climate of the island, the vegetation of Iceland has a composition which cor- responds most nearly to that of Scandinavia and South Greenland. With the exception of the species found only in Iceland, there is only one species (Bryoxiphium norvegicnm) which has not been found in the other parts of Europe, but which has its home in North America, and one species (Tortilla obtusifolia) which I do not think has been found in Scandinavia. The other species are all common to Iceland and Scandinavia. At present it is not possible to compare the Bryophyte flora of Iceland and Greenland, partly because there is no collective account of the distribution of the species found in Greenland, and partly because the older Greenland collections and lists of species greatly need revision. The Bryophyta found in Iceland can be arranged in four geo- graphical groups (Arnell and Jensen, 1910, p. 238): 1. Ubiquitous species, which are almost equally distributed over the whole of North Europe as far as north of the Arctic Circle. 2. Meridional species, which are most frequent in Southern Scandinavia and far rarer in Northern Scandinavia. 3. Boreal species, which are more frequent in Northern than in Southern Scandinavia, and have their main distribution below the tree-limit. 4. Alpine species, which have their main distribution above the tree-limit. In Table II and in the following Tables the plant-geographical character of the species is denoted by the initial letters u, m, b and a, which are prefixed to the name of the species. Icel. indicates that the plant is known only from Iceland. As already mentioned, the species found only on warm soil - almost all of which belong 630 A. HESSELBO to the meridional group are not included in the present or fol- lowing sections. Table I. The Plant-geographical Groups. u m b a Icel. HepaticcC 28 18 19 22 Sphagnales 11 2 4 Musci veri 93 53 88 86 6 Total . . . 132 73 111 108 6 Of greatest interest in this connection is the comparatively large group of meridional species, which comprise about VG of all the species. According to their distribution in the different districts of Iceland they can be divided as follows: a. Found only in the Southern part of Iceland (South Iceland and most nearly adjacent parts of South-east and South-west Iceland). Reboulia hemisphserica. Fegatella conica. Fossombronia Dumortieri. Aneura multifida. Marsupella Funckii. Jamesoniella autumnalis. Lophozia excisa. Lophocolea cuspidata. Lepidozia setacea. Frullania fragilifolia. Lejeunea cavifolia. Sphagnum papillosum. Weisia crispata. viridula. Trichostomum littorale. Barbula unguiculata var. cuspidata. Tortula muralis. mucronifolia. Hedwigia albicans. Orthotrichum anomalum. saxatile. cupulatura. Mnium tmdulatum. Leucodon sciuroides. Anomodon viticulosus. Thuidium tamariscinum. Philiberti. Isothecium myurum. Scleropodium purum. Eurhynchium piliferum. Swartzii. Stockesii. Rhynchostegium murale. Plagiothecium depressum. elegans. Amblystegium fluviatile. Hypnum molluscum. b. Most common in South Iceland, rarer in the other parts of the island. Madotbeca Cordaeana. Barbula cylindrica. Mnium serratum. Catharinea undulata. Neckera complanata. Thuidium delicatulum. Thamnium alopecurum. Rhynchostegium rusciforme. Camptothecium lutescens. Hypnum commutatum. THE BRYOPHYTA OF ICELAND 631 c. Found only in a single locality, or in a few localities, in the different parts of Iceland. Haplozia crenulata. Lophozia barbata. Lophocolea minor. Diplophyllum obtusifoliura. Sphagnum angustifolium. Dicranum Bonjeani. Trematodon ambiguus. Fissidens bryoides. Leplodontium tlexifolium. Barbula fallax. Bryum bimum. Mnium cuspidatum. stellare. Cylindrothecium concinnum. Eurhynchium strigosum. Amblystegium serpens. Juratzkanum. trichopodium. Hjrpnum Sommerfeltii. Sendtneri. d. Frequent everywhere, or in large parts of Iceland. Radula complauata. Common in South, East and West Iceland, absent from North Iceland. Rhacomitrium aciculare. Very common all over Iceland. Mnium hornum. Common, especially in South Iceland, rarer in North Iceland. Pogonatum nanum. Common in several parts of West and South-west Iceland. Metzgeria furcata. Common over the whole of Iceland. The majority of the meridional species (a = 37 species and b = 10 species) have a decidedly southerly distribution. Of the species belonging to group c only Lophozia barbata, Diplophyllum obtusi- folium and Bryum bimum have been found, each in a separate locality in East Iceland. The other habitats are equally distributed over South, West and North Iceland. Table I shows that there is an almost equal number of Boreal and Alpine species and a somewhat larger number of Ubiquists, but in order to obtain a really comprehensive view of these groups, showing which has the greatest importance with regard to the com- position of the vegetation, it is also necessary to investigate how many species with a somewhat high degree of frequency are con- tained in each group. If all the species are included, the frequency of which throughout a larger part of Iceland (besides South Iceland) is expressed by the figure 3 (see p. 644) or upwards, the number of species contained in each group will be as follows: — 632 A. HESSELBO Table II. Species with the Frequency of 3 or upwards throughout a larger part of Iceland. u m 1) a Hepaticae 15 3 7 u Sphagnales 4 Musci veri 55 4 49 94 Total . . . 74 7 56 33 170 Group 1. Ubiquitous species. *Marchantia polymorpha. *Aneura pinguis. *Pellia Neesiana. *Alicularia scalaris. *Lophozia quinquedentata. ventricosa. Mulleri. *Plagiochila asplenioides. •-••• Sphagnum Girgensohnii. teres. Warnstorffii. rubellum. Gymnostomum rupestre. Anoectangium compactum. *Dicranum scoparium. congestum. Ceratodon purpureus. *Ditrichum flexicaule. *Did3^modon rubellus. *Tortella tortuosa. Tortula subulata. ruralis. Schistidium maritimum. apocarpum. gracile. Rhacomitrium heterostichum. canescens. hypnoides. Amphidium Mougeottii. Ulota maritima. Orthotrichum rupestre. Encalypta rhabdocarpa. * *Cephalozia bicuspidata. Hampeana. *Blepharostoma trichophyllum. *Ptilidium ciliare Scapania dentata. undulata. *Frullania Tamarisci. Funaria hygrometrica. *Leptobryum pyriforme. *Pohlia cruda. *Bryum inclinatum. argenteum. pallens. \rentricosum. *Mnium affine. Seligeri. punctatum. Meesea triquetra. *Aulacomnium palustrc. *Bartramia ityphylla. *Philonotis fontana. Pogonatum urnigerum. Pol}rtrichum juniperinum. Diphyscium sessile. Fontinalis antipj'retica. Antitrichia curtipendula. *Pterigynandrum iiliforme. :i:Climacium dendroides. Brachythecium albicans. Plagiothecium Rccseanum. *Hypnum stellatum. uncinatuni. THE BRYOPHYTA OF ICELAND 633 *Hypnura exannulatum. filicinum. cupressiforme. Lindbergii. strain incum. Group 2. Metzgeria furcata. Madotheca Cordaeana. Radula complanata. *Rhacomitrium aciculare. *Acrocladium cuspidalum. *Scorj)idium scorpioides. *Hylocomium proliferum. parietinura. squarrosum. Meridional species. Mnium hornuni. Catharinea undulata. Camptothecium lutescens. Group 3. *Alicularia geoscypha. *Lophozia lycopodioides. Kunzeana. *Chiloscyphus polyanthus. *Andreaea petrophila. *Dichodontium pellucidum. *Oncophorus \Yahlenbergii. virens. Dicranella squarrosa. crispa. Dicranum Blvttii. w Fissidens osmundoides. *Blindia acuta. *Distichium montanum. Tortella fragilis. Grimmia torquata. *Rhacomitrium sudeticum. fasciculare. *Amphidium lapponicum. Encalypta ciliata. Dissodon splachnoides. Splachnum sphsericum. vasculosum. *Pohlia gracilis. *Mniobryum albicans. Bryum purpurascens. lacustre. affine. cirratum. Boreal species. *Cephalozia pleniceps. *Scapania irrigua. curt a. *( * Bryum pallescens. Duvalii. *Mnium cinclidioides. *Paludella squarrosa. *Meesea trichoides. *Catoscopium nigritum. *Philonotis tomentella. *Timmia austriaca. Polvtrichum strictum. V gracile. *M\7urella julacea. tenerrima. Lescuraea filamentosa. Thuidium lanatum. *Camptothecium nitens. Brachvthecium reflexum. V rivulare. Plagiothecium pulchellum. *Hypnum polygainum. revolvens. Kneiffli. decipiens. falcatum. giganteum. Hvlocomium rugosum. */ O Group 4. Alpine species. *Gymnomitrium concinnatum. Pleuroclada albescens. *Haplozia cordifolia. Anthelia julacea. atrovirens. Juratzkana. Lophozia quadriloba. *Scapania subalpina. alpestris. The Botany of Iceland. Vol. I, part II. 41 (334 A. HESSELI3O *Dicranoweisia crispula. Aongstrcemia longipes. Dicranum ialcatum. Starckei. molle. Desmatodon latifolius. *Schistidium rivulare. Grimmia Doniana. funalis. Tetraplodon bryoides. *Pohlia commutata. Brvum a re ti cum. *Mnium orthorrhynchum. Conostomum boreale. Philonotis seriata. Psilopilum laevigatum. hercynicum. *Polytrichum alpinum. sexangulare. Amblystegium Sprucei. *Hypnum revolutum. alpestre. ochraceum. sarmentosum. The species to which an asterisk has been prefixed have every- where, or throughout the larger part of Iceland, the degree of fre- quency expressed by figure 4 (see p. 644), and consequently they constitute the bulk of the vegetation. Groups 1 and 3 include con- jointly 75 (41 -f- 34) species, while group 4 has 15, and group 2 only one species which is very common everywhere. IV. THE ALTITUDINAL DISTRIBUTION OF THE SPECIES. THERE are only a few species which are equally common in the low land and on mountain heights. The majority of them are either Lowland forms, which rapidly decrease in frequency above a certain altitude and at last disappear completely, or Alpine forms which have their main distribution at greater heights above sea- level and decrease in frequency downwards. In countries with a continental climate it is, as a rule, not difficult to draw a some- what sharp limit for the altitudinal distribution of plants, but the conditions for survey are far less favourable in a country like Ice- land, where a cold and damp insular climate prevails in the coastal districts. On account of the low summer temperature, the majority of the Alpine species can thrive as far down as the low land, and conversely many of the lowland mosses will be able to establish colonies in favourable localities, which are situated essentially higher than their usual limit of growth. In South Iceland, for instance, I have seen a southern slope, at an altitude of above 500 metres, which was covered with species of Hylocomium together with other species belonging to the same formation. As regards Iceland a fairly distinct boundary line may be drawn between the Lowland and Highland formations by taking the upper limit of the heather moor (and of the birch) as a basis for the classification (Helgi Jonsson, 1895—1899—1900); it is then seen that the upper limit of growth of a very great number of Bryophyta nearly coincides with the upper limit of the heather moor. The upper limit of the heather moor varies somewhat in the different parts of Iceland, and is also in a high degree dependent on local conditions such as shelter, direction of exposure, and conditions per- taining to moisture. In East Iceland the boundary line lies, as a rule, at about 300 metres, and the same is the case in the greater part of South-west, West and North Iceland. Around Myvatn, ac- 41* 036 A. HESSELBO cording to Thorodd sen's statement, the birch coppices ascend to 550 metres. In North-west Iceland the birch coppices in Dyrafjordur ascend to about 270 metres, and around Isafjardardjup probably not very far above 200 metres. In South Iceland the upper limit of the heather moor generally lies at an altitude of 300—350 metres, but in sheltered valleys both birch coppices and heather moor may be met with at an altitude of above 500 metres. On the whole, the upper limit of the heather moor may, however, be reckoned to lie, on an average, at an altitude of about 300 — 350 metres. All that is situated above this limit is in the following designa- ted the Alpine region, since the willow region which occurs in the mountains of Scandinavia and Central Europe is not typically de- veloped in Iceland": not, at any rate, in the coastal districts. The reason for this must in a great measure be sought in the geological structure of the country. The gradually-ascending or terrace-formed land near to the coast rises to a height of 200—300 metres, and from here the mountains almost everywhere shoot abruptly upwards to a height of 600—700 metres, right up to the plateau on the mountain summit, from which again a few peaks or rock-masses protrude. This leaves very little room for vegetation between 300 and 600 metres, with the exception of the valleys, which are, as a rule, very narrow. This is very decidedly noticeable in North-west and East Iceland, where almost everywhere along the coasts, from a quite narrow coast-land, the mountains rise abruptly to an almost constant height of 600 metres, so that only at the head of the val- leys do terraces occur at various levels as far upwards as the mountain heights. In North Iceland, especially towards the east, the country rises more gradually up towards the interior high land, and there at any rate somewhat inland — willow coppices and willow swamps occur also, but their Bryophyte vegetation has been very little investigated. Taking the above as a basis the vegetation may be classified into zones, according to altitude. A. The Lowland region which reaches to the upper limit of the heather moor and the birch. B. The Mountain region which includes slopes and flats to a height of about 600 metres. C. Alpine Heights (the Snow region) to which is reckoned all that is situated higher than about 600 700 metres. The vegetation there is very poor in species, and is strongly affected THE BHYOPHYTA OF ICELAND 637 by the severe climate and the snow, which remains over ex- tensive tracts till late in the summer, and saturates the soil with ice-cold snow-water. In the following table the first column consists of the species which have been found in the Lowland region, the second column the species which have been found in the Mountain region, and the third the species which have been found in the Snow region. A cross (4-) indicates that the species has its main distribution in the region in question; a dash ( — ) indicates that the species in question decreases in frequency and extends to a more or less high level (or low level) in the region in question, and a dot (•) indicates, that the species has been found only in a few places close to the boundary of the region to which it belongs, or that it has, on the whole, been found so scantily that no opinion can be formed with regard to its distribution within the different altitudinal regions. Table III. The Distribution of the Bryophyta in the different Altitudinal Regions. ' • e 0 o eo a Q. D g o 0 cc ,— 0 ^^ to o > o X5 < a § co o •M 0, a S o CO ! 0 CO S 0 o CO 0> 1 < Alicularia scalaris 4- 4- Hepaticae. °"coscypha . i 4- 1 4. .±. Sauteria alpina Eucalyx subellipticus .... i 4- \ • 1 Reboulia hernisphaerica 4- Haplozia crenulata i 4- Fimbriaria pilosa i • sphaerocarpa I • • Fegatella conica 4- cordifolia 4- Freissia conimutata i 4- riparia i 4- Marchantia polymorpha .... i 4- atrovirens i 4- Aneura multifida i -u pumila i^ latifrons i 4- Jamesoniella autumnalis . Pellia Neesiana i 4- • Sphenolobus minutus Metzgeria furcata i 4- politus Blasia pusilla . .• i 4- Lophozia quinquedentata 4. 4- 4- Fossombronia Dumortieri . . . Gymnomitrium coralloides. T 4- lycopodioides . ... Fhcrckei i + 4- i 4- 1^ * v/ concinnatum 1 4. 4- quadriloba \ 4- i 4_ varians i • 1 Kunzeana \ 4- i 4. revolutum . . • barbata \ 4- 1^ Marsupella Funckii • ventricosa . . \ 4- 4- 4- ~ emarginata • Wenzelii i 4- i^ aquatica . • — aloestris . i 4- 4- 4- 638 A. HESSELBO Table III. The Distribution of the Bryophyta in the different Altitudinal Regions (continued). • E 0 0 cc o •+-> s. p a o o CO 0 o *V-l £ 0 0 tO 0 > c ^ < • 2 o 0 07 C — r^ 5 o o iC o ot S 0 o cc OJ c ^^ < Lophozia excisa Frullania Tamarisci 4- Schultzii _i I fragili folia ... . i 4- Mulleri Madotheca Cordseana i Hornschuchiana. . Lejeunea cavifolia ... 4- heterocolpos i i Gvmnocolea inflata. i Sphagnales. *J Plagiochila asplenioides 4- • Sphagnum medium 4- Leptoscyphus anomalus i papillosum ... . i 4- Lophocolea cuspidata i 4- inundatum .... i j- minor i + (iravetii i Chiloscvphus polyanthus i + • conipactum Harpanthus Flotowianus .... 4- teres 4- 4- Cephalozia bicuspidata i 4- squarrosum . . i 4- I ambigua i fimbriatum pleniceps 4- Girgensohnii 1 4- media i Russowii . . i Pleuroclada albescens 4- \Va rn storf fl i 4- var. islandica . . . 4- 1 rubellum i^ -f Cephaloziella Hampeana . i 4- acutifolium i 4- rubella i 4- subnitens i 4- Odontoschisma elongatum. . . i 4- Lindbergii \ denudatum . . 1 • riparium 4- Macouni . . . 4. — an^ustifolium i Lepidozia setacea i . Blepharostomatrichophyllum Anthelia julacea + 4- + Musci veri. Andreaea petrophila 4. 4. ~ _l_ Juratzkana i 4- 4- Gvninostomum rupestre i7 4. 1 Ptilidium ciliare 4- i 1 Hymenostvlium curvirostre i _|_ Diplophvllum albicans i 4- Ancx?ctangium compactum i^ 4_ ~ obtusifolium. . i Weisia crispata 4- Scapania subalpina 4- > viridula i 4- remota i Wimmeriana. . \ irrigua • Dicranoweisia crispula _u -I- _1_ uliginosa . . . compacta i 1 1 paludosa Cvnodontium uolvcaruum . dentata 4. */ L » Dichodontitim pellucidum,. . -i- undulata i 4. Aongstroi'miu longipes . . . i 4- curta i 4- Oncophorus virens i 4_ Bartlingii . i Wahlenbergii _L i^ 4_ Radula complanata . . 4- Dicranella squarrosa l^ 4- i^ 4- Frullania dilatata. i^ — Schreberi . i 4- \^ THE BRYOPHYTA OF ICELAND (539 Table III. The Distribution of the Bryophyta in the different Altitudinal Regions (continued). a o o CO 3 r* •— * D a o o CO o o CO a o o cc u >• 0 <••» < a 0 o ^. o — a. D G 0 T ?: E -^ ^ ^. < Dicranella crispa 4- Tortella fragilis 4- cerviculata i 4- Barbula unguiculata i + subulata 4- fallax i 4- Dicranurn fulvelluni i 4- cvlindrica i 4- Andersonii 4- 1 icmadophila i 4. falcatum i I Desmatodon latifolius i^ 4- — Blvttii 4- 4- cernuus . i Starckei 1 4- I 4- Tortula obtusifolia molle I 4- \ muralis 4- Bonjeani -I- 1 subulata 4- angustum 4- mucronifolia i 4- majus i 4- ruralis .... i 4- i 4- aciphvlla i fuscescens i 4- Scliistidium maritimuni 4- coiig'esturn i 4- 4~ apocarpurn i 4- 4- spadiceum i 4- °'racile i 4- i^ 4- elongatum i 4- coiifertum i 4- i Campylopus Schirnperi i 4- alpicola i Trematodoii ambiguus i 4- v rivularis 4- Fissidens brvoides i 4- Grinnnia conirnutata .... i^ • osmundoides i 4- Doniana + decipiens i alpestris n^ 4_ adianthoides 4- — ovata . i 4- Blindia actita i 4- incurva i Ceratodon purpureus i 4- 4- patens . 4- Ditrichum tortile 4- i^ funalis i 4- nivale i torquata ... i + homomallum .... tlexicaule + 4- 4_ Rhacomitrium sudeticum . . . heterostichurn i + 4. + — Saelania cresia i 4- i microcarpum i Distichium montanuni i 4- 4- w canescens 4. 4. 4. inclinatuni i 4- i hvpnoides i 4. T 4_ ~ i 4_ Bryoxiphium norvegicum . Pottia Heimii i + 4- fasciculare . . . aciculare i^ + 4- + i + latifolia i Hedwigia albicans. . i 4- Didymodon rubellus 4- Aniphidiuni lapponicuni i^ _|_ rufus i^ 4- • Mougeottii . . \ 4- Leptodontium flexifolium . . . i Ulota phvllantha i^ 4. Trichostomum littorale Orthotrichum anomalum.. . . i^ 4_ Tortella inclinata saxatile i 4- — tortuosa . 4- — cunulatum. 4- 640 A. HESSELBO Table III. The Distribution of the Bryophyta in the different Altitudinal Regions (continued). e 0 o CO 0 — 0, u B o 0 CD 1 O o CO S 0 0 CD a D S 0 o CD 1 O 0 CO S 0 0 CO a> 0 -Q < Orthotrichum rupestre -1- • Bryum uliginosum . . . 4- Sturmii ...... 4- fallax i Killiasii 4- oeneum . . ... 4- Blyttii 4- bimum i laevigatum .... i • affine 4- Encalypta ciliata 4- cirratum i 4- rhabdocarpa 4- intermedium i 4- contorta i pallescens . . . i 4. Dissodon splachnoides ...... 4- 4- subrotundum i Tetraplodon bryoides i 4- i capillare 4- Splachnum sphaericum 4- • csespiticium i 4- vasculosum i 4- 4- • comense i Funaria hvgrometrica 4- i elegans 4- Leptobryum pyriforme 4- argenteumt i 4. Anomobryum flliforme i 4- neodamense i • concinnum . . . 1 * Duvalii 4- • Plagiobryum Zierii 4- pallens i 4- • demissum 1 • ventricosum i^ 4- 4- Pohlia acuminata 4- arcticum i 4- i polymorpha pendulum i 4- cruda 4- 4- Brownii i • nutans i 4- i Mnium hornum 4. cucullata \ 4. 4. orthorrliynchum i -|_ Ludwigii i 4- i serratum i 4- commutata i 4- 4- spinosum i 4- gracilis i 4- 4. undulatum i 4- Rothii 4- \ i cuspidatum i 4- tenuifolia i 4- medium 1^ 4- grandiflora \ 4- affine i^ 4- proligera \ Seligeri \ 4- Mniobryum albicans 4_ 4_ 4. stellare i 4- Bryum purpurascens \ 4- i i cinclidioides i 4- lacustre i 4- punctatum i 4- Kaurini i sub°'lobosum i 4_ archangel icum 4_ Cinclidium stygium i^ 4- 4- Jorgensenii n Paludella sciuarrosa ......... i 4- i inclinatum 4. Amblvodon dealbatus i • retusum i 4- Meesea trichoides 4- islandicum i triquetra i 4- Groenlundii Catoscopium nigritum i 4- • calophvllum . • Conostomum boreale . i 4- 4- THE BRYOPHYTA OF ICELAND 641 Table III. The Distribution of the Bryophyta in the different Altitudinal Regions (continued). £ 0 o CO 0 -l-> c. £ £ o o - - 0 o CO E o o o > j§ < 4 £ 0 •***• 0 *-> a D G 0 o -<^ 1 0 0 00 e 0 o ^ V 0 J2 < Aulacomnium palustre 4- 4- Pterigvnandrum liliforme . . . 4- turgidum I 4- 1 4- Lescuraea decipiens i . Bartramia itvphvlla 1 4- i 4- radicosa Plagiopus CEderi i i fllamentosa 4- Philonotis fontana 4- 4- 4- Breidleri i 4- Arnellii 1 • i 1 patens 4- T seriata 4- 4- Heterocladium squarrosulum i 4- tomentella 4- i 4- Thuidium tamariscinum .... 4- Tinimia norvegica i 4- i delicatulum i 4- i 4- Philiberti i 4- Catharinea undulata i 4- abietinum i 4- Oliaiotrichum hercvnicum i 4- 4- lanatum i 4- */ Psilopilum Isevigatum 4- i i Orthothecium rufescens i Pogonatum polytrichoides. . . dentatum var. minus urnigerum i + • 4- • intricatum.. . . chryseum .... Cvlindrothecium concinnum. + + — Polvtrichum alpinum i 4- 4- Climacium dendroides 4- formosum i i Isothecium myurum !^ 4- gracile 4- tenuinerve i 4_ sexangulare .... var. tenellum. \ • 4- + Homalothecium sericeum . . . Camptothecium lutescens . . . nitens i + + 4- 4- piliferum i 4- Brachvthecium Mildeanum.. \ 4- 1 juniperinum . . . strictum i + -f — salebrosum.. collinum . . . i + — commune i 4- populeum. . . 4- Swartzii i 4- velutinum . . i 4- Diphvscium sessile . . i 4- 4_ • glaciale i 4- 4- Fontinalis antipyretica i 4- i rettexum .... i 4- 1 islandica i — longipilum . . 1 longifolia glareosum . . . 4- thulensis • albicans .... i 4- androgvna — ervthrorrhizon i 4- Leucodon sciuroides 4- tf rivulare i 4- Antitrichia curtipendula .... Neckera complanata i + 4- latifolium. . . Scleropodium purum i 4- Mvurella julacea i 4- • Eurhynchium strigosum .... i 4- tenerrima i 4- • diversifolium . i • » Leskea nervosa i 4- cirrosum 4- catenulata . . i piliferum i 4- Anomodon viticulosus . 4- — Swartzii . i 4- 642 A. HESSELBO Table III. The Distribution of the Bryophyta in the different Altitudinal Regions (continued). G o 0 CO o -i-> a D 5 o i I c^^ o CO £ o 0 tO o o ^ <5 5 o 0 CO o •f-J Q| C3 5 o o ^5 0 co • 2 o ^ ^ o > o <~\ < Eurhynchium Stockesii 4- Hvpnum filicinum 4- Rhynchostegiurn murale .... i 4- curvicaulc i 4- rusciforrne . i 4- decipiens 4- Thamnium alopecurum i 4- commutatum i 4- Plagiothecium silvaticum . . . Roeseanum. . . denticulatum . i + + 4- • v. fal- catum molluscum i + 4- pulchellum . . i 4- imponens i 4- depressum . . . i 4- Rambergeri i^ elegans i • revolutum 4- Amblvstegiuni Sprucei 4- cupressiforme i 4- fluviatile i hamulosum \ 4- serpens 4- callichroum i 4- Juratzkanum . i 4- Lindbergii i 4- littorale i 4- palustre i 4- compactum . . i 4- arctic um i salinum i 4- alpestrc 4- trichopodium. i 4- alpinum i 4- Hvpnurn Sommerfeltii i ocliraccum i 4- chrysophvllum . 4- cordifolium i 4- +} i +> protensum ! 4- Richardsonii . i 4- stellatum i 4- 4_ £*iganteum . ... i 4- polvgamum i 4- 1 stramineum i 4- 4- intermedium ...... i 4- 4- sarmentosum i j_ 1^ 4- revolvens i 4- 1 4- trifarium uncinatum ........ i 4- i 4- • turgescens 4- Sendtneri i \ Acrocladium cuspidatum i 4- Kneiffii 4- Scorpidium scorpioides . . . i 4- exannulatum i 4- 4- Hylocomium proliferum .... i 4- 4- var. pur- purascens . — var. Rota?. i + 4- i + pyrcuaicum . . . parietinum .... loreum i + 4- i var. ser- ratum. 11 ui tans i • 4- triquetrum .... squarrosum . . . rusjosum + + 4- * • v. falcatum. i^ • i Table I shows that of the 424 species enumerated in it (the habitat of Sphenolobns saxicola is not known) 416 occur in the low land, and that only 8 species (Gymnomitrium imrians, Pleiiroclada THE BKYOl'HYTA OF ICELAND 643 albescens, Scapania remota, Dilrichiiin nivale, Pohlia polymorpha, P. Lndwigii and Brachythecium (jlaciale) have not been found below the upper limit of the birch. In the Mountain region the number of species is as follows: 42 Hepatica3 5 Sphagna 134 Musci veri 181 Total species. Of these, however, 10 Hepaticse and 31 Musci veri have been found only in the lowest part, at the boundary towards the Low- land region, whereby the number of species which in reality bi- long to the Mountain region, is reduced to 140. Of these, 2 He- paticse, viz. Gymnomitrium varians and Scapania remota and 3 Musci veri, viz. Ditrichiun nivale, Pohlia polymorpha and P. Ludwigii have been found only in this region. In the Snow region the number of species is as follows : 16 Hepaticse, 42 Musci veri, total 58, of which, 6 Hepaticas and 10 Musci have been found only in a few localities and cannot be re- garded as belonging to this region. In all, 42 species remain, of which, however, only 8 Hepaticse and 20 Musci veri are fairly fre- quent, while the others have been found only in a few localities. The majority of the species belong to those which are of equal frequency at all altitudes, and only 4 species (Pleiiroclada albescens, Dicranum falcatum, Pohlia cucullala and Pohjtrichnm sexangulare) can be designated true Snow-region species. The number of species decreases rapidly as the height above sea-level increases, and even at the upper limit of the heather moor the number falls to about 40 % of the total number of species. Above a height of about 600 metres the number scarcely reaches u v 15 % of all the species. V. THE HORIZONTAL DISTRIBUTION OF THE SPECIES. IN order to obtain a correct notion of the importance of each plant- species within a floral district it is necessary to know not only their distribution in the different parts of this district, but also their relative abundance (number of individuals) in comparison with other species. The following Table gives a summary of all the Bryophyta found in Iceland, with the exception of the species growing in warm soil, since, as regards these species, it is chiefly the heat of the soil and not the climatic conditions which determine their distribution. The frequency within the different districts is indicated by the figures 1--4, so that 1 indicates rare or very scantily occurring species; 2. those that occur here and there or only in a comparatively few localities and not in abundance; 3 frequent, but as a rule playing no important part in the moss-covering, or occurring only locally in abundance; and 4 the common and abundantly occurring species* The majority of the species are not equally distributed in all the different altitudinal regions, and the frequency is therefore reckoned relatively to the region in which each species is most widely distri- buted. As regards species which grow only in quite definite areas (for instance littoral species) the frequency is reckoned separately. The figures in the table are, however, in many cases somewhat doubtful, since many districts are too superficially investigated to allow one to form an opinion as to the frequency of the less com- monly occurring species. This is the case, for instance, as regards the majority of the districts of East Iceland situated above an alti- tude of 300 metres, because in June, when I travelled through this part of the country, the mountains were still for a great part snow- covered, which in connection with continual fog made investiga- tion almost impossible. It must also be noted that the table is based only on the THE BRYOPHYTA OF ICELAND 645 coastal districts, and on the lo\v land with the neighbouring heights. The high land of the interior, which is about 90,000 km2, in dimen- sion and, usually, 600 — 1000 metres in height, is from a botanical point of view practically unknown. Outside the Jokulls it consists almost everywhere of gravelly flats which are practically bare of vegetation. According to Thoroddsen, however, there are in some places extensive mountain -bogs, but the Bryophyte vegetation of these is quite unknown. Table IV. The Frequency of the Species in the different Districts of Iceland. E. I eel. X. Icel. NW. Icel. W. Icel. S. Icel. a Hepaticae. Sauteria alpina 1* m Reboulia hemisphaerica 3* a Fimbriaria pilosa 1* 1* m Fegatella conica 4 u Preissia commutata 2* 1 2 3* u Marchantia polymorpha 4* 4* 4* 4* 4* u Aneura pinguis 4 4 4* 4 4* m multifida 1 u latifrons 1 1 1 u Pellia Neesiana 4 4* 4 4 4 m Metzgeria furcata 3 3 3 3 4 u Blasia pusilla 2 1 m Fossombronia Dumortieri 1 a Gvrnnomitrium corallioides 3 2 3 2 a concinnatuni 4* 4* 4* 4* 4* a varians 1 1 a revolutum 1 Tl Marsupella emarginata 1 2 u aquatica 1 m Funckii 1 1 u Alicularia scalaris 4* 4* 4* 4* 4* b — e'eoscvoha 4* 4* 4* 4* 4* a Eucalvx subellipticus 2* 1* 2* 1* 1* b Haplozia sphaerocarpa 1 a cordifolia 4* 4* 4* 4* 4* ^b 3* 3* 3* 3* 3* 3* 1) pumila 1* m crenulata 1 1 m Jamesoniella autumnalis . 1 (54(5 A. HESSELBO Table IV. The Frequency of the Species in the different Districts of Iceland (continued). • E. Icel. N. Icel. NW. Icel. W. Icel. S. Icel. tl Sphenolobns minutus 1 1 1 b saxicola? a politus 1* 11 Lophozia quinquedentata 4 4* 4* 4 4 b lycopodioides 4 4 4 4 3 b Fld-'rckci 4 2 a quadriloba 3 2 9 2 2 b Kunzeana 4 4 4 4 4 m barbata 1 2 i u vcntricosa 3 3 4* 3 3 a Wenzelii 1 1* 1* 1 a alpestris 4 4 4* 4* 4* m excisa 1* b Schultzii 1 1 1* u Mulleri 3 3 3 3 •* it Hornschuchiana 2 1* 1 2 b heterocolpos 1 1 1 i u Gvmnocolea inflata 1 u Plagiochila asplenioides 4 4 4 4 4 11 Leptoscypbus anomalus 1 m Lophocolea cuspidata 2 m minor 1 1 1) Chiloscyphus polyanthus 4 4 4 4 4 1) Harpanthus Flotowianus I 1 4 2 11 Cephalozia bicuspidata 4* 4* 4* 4* 4* a ambigua 1* I) pleniceps 3* 3* 4* 3* 9 }) media 1* 1* a Pleuroclada albescens 3 3 4 2 a 11 var. islandica. . . Cephaloziella Hampeana 4* 1 4* 4* 4* 2 4* u rubella 1 1 2 1 1 u Odontoschisma elongatum (\ 1 3 1 u denudatum 1 a Macouni 1 1 m Lepidozia setacea 1 u Blepharostoma trichophyllum 4 4* 4 4 4* b Ghandonanthus setiformis? a Anthelia julacea 3* 3* 3* 3* 3* a Juratzkana 4* 4* 4* 4* 4* 11 Ptilidium ciliare 4 4 4 4 4 11 Diplophyllum albicans 3 3 m — obtusifolium . 1 1 THE BRYOPHYTA OE ICELAND IM7 Table IV. The Frequency of the Species in the different Districts of Iceland (continued). a Scapania subalpina a rcmota b irrigua b uliginosa b paludosa u dentata u — imdulata b curta a Bartlingii m Radula complanata m Madotheca Cordieana u Frullania dilatata u Tamarisci in fragilifolia m Lejeunea cavifolia Sphagnales. ]) Sphagnum medium m papillosum u inundatum u Gravetii b compactum u teres u squarrosum u fimbriatum n Girgensohnii .. . . b Russowii u Warnstorffii ti rubcllum u acutifolium u subnitens b Lindbergii u riparium m angustifolium. . Musci veri. 1) Andreiea petrophila u Gymnostomum rupestre . . . 1) Hymenostylium curvirostre u Anoectangium compactum. . m Weisia crispata m viridula a — Wimmeriana. E. Icel. 4? 1 3* 4* 4* 3 2 3 3 4* 1 N. Icel. 4* 1 4* 1* 4* 4* 4 1 2 3 3 3 1 4* 3 1 NW. W. Icel. Icel. 4* 4 3 3* 4* 4* 2 4 3 2 3 3 3 1 1 3 4* 4 2* 4* 4* 3 3 1 4 1 1 2 3 3 3 3 1 2 1 3 1 3 1 S. Icel. 4* 4* 3* 4* 4* 1 3* 4 4 1 3 2 2 1 1 4 1 3 1 3 3 1 2 4* 3 3* 4 1* 1* 648 A. HESSELBO Table IV. The Frequency of the Species in the different Districts of Iceland (continued). E. Icel. N. Icel. NW. Icel. W. Icel. a Dicranoweisia crispula.... a compacta. . . u Cynodontiura polycarpon . b Dichodontium pellucidum a Aongstroemia longipes b Oncophorus Wahlenbergii b virens b Dicranella squarrosa u Schreberi b crispa b subulata u cerviculata a Dicranum fulvellum a Andersonii a falcatum b Blyttii a Starckei a molle m Bonjeani b angustum u majus u scoparium u fuscescens u congestum a spadiceum a elongatum a Campylopus Schimperi . . . m Trematodon ambiguus . . . , m Fissidens bryoides b osmundoides. . . , u adianthoides u decipiens , b Blindia acuta u Ceratodon purpureus u Ditrichum tortile a nivale , u homomallum . , u flexicaule a Sselania caesia b Distichium montanum u inclinatum. . . a Bryoxiphium norvegicum , u Pottia Heimii . 1* 4* 3 4* 2 4* 1* 2* 1* 4* 1* 1 3 4 2 4* 2* 1 1 1 4* 2* 4* 1* 9* 4* 1 4* 3* 4* 4* 3* 1 4* 1 9* 1* 4* 1* 1 1 4 1 2 1 1* 3 1* 4* 3* 1 4 2* 4* 2* 1 4* 4* 4 4* 1 2 3* 3* 4* 4* 1 3 4* 4* 9 3 4* 3* 4* 1* 4* 2 4* 4* 2 1 4* 2* 3* 4* 3* 2 2 1 4* 1 3 1 2 2 1 3* 2* 1 4* 3* 2* 4 3* 4* 3* THE BRYOPHYTA OF ICELAND 649 Table IV. The Frequency of the Species in the different Districts of Iceland (continued). E. Icel. N. XW. Icel. Icel. W. Icel. S. Icel. a Pottia latifolia ....... ............... u Didymodon rubellus ................. 4* b rufus .................... 1 m Leptodontium flexifolium ............ m Trichostomum littorale ..... ......... u Tortella iiiclinata .................... 1 u tortuosa .................... 4 b fragilis ..................... 3 111 Barbula unguiculata var. cuspidata . . . m fallax ....................... m cjTlindrica ........... ....... a icmadophila ................. 1 a Desmatodon latifolius ................ 3* a cernuus ................. a Tortula obtusifolia .................. m muralis ............ ........ u subulata .................... 3* in mucronifolia ................ u ruralis ...................... 2* a aciphylla .................... u Schistidium maritimum .............. 3* u apocarpum .............. 3* u gracile .................. 4* b confertum ............... 1* a alpicola ................. a var. rivularis ..... 4* b Grimmia commutata ................ a Doniana ................... 3* a alpestris .................. 1 b ovata ...................... 2 a incurva .................... 1 u patens ..................... 1 a funalis ..................... 4* b torquata ................... 2 b Rhacomitrium sudeticum ............ 4* b microcarpum .......... u heterostichum ......... 3 u canescens ............. 4* u hypnoides ............ 4 b fasciculare ............ 4* in aciculare ............. 4* m Hedwigia albicans .................. b Amphidium lapponicum ............. 4* The Botany of Iceland. Vol. I. part II. 1* 4* 1 1 4 3 1 1 2* 1* 3* 3* 4* 2* I* 4* 1 * 4* 1 3* 1 2 4 4 3* 4* 3 3* 1* 3* 3* 4* 4* 2 4* 2 4* 4 3* 4* 4* 1 1 4 3 1 1 1 1 2* 3* 2 3* 3* 4* 4* 1 3* 1 4* 3 3* 4 4 4 4* 4* 4 3 1 1 3* 1* 1* 3* 1* 2 3* 3* 4* 3* 1* 4* 4 3* 4 4 4 4* 4* 1 4* 42 650 A. HESSELBO Table IV. The Frequency of the Species in the different Districts of Iceland (continued). E. Icel. N. Icel. N\V. Icel. W. Icel. S. Icel. Amphidium Mougeottii 3 •) 3 4 4 Ulota phyllantha 3 3 3 3 3 Orthotrichum anomaluni 1* — saxatile 1* cupulatum 1* rupestre 3* 3* 3* 3* 3* — Sturrnii 1* 1* Killiasii 1* 1* 9 Blvttii 2* 1* 1* 1* Itevigaturn 2* 1* 1* 1) Encalvpta ciliata . . . 3* 2* 3* 3* rhabdocarpa 3* 3* 3* 3* 3* coiitorta . 1 b Dissodon splachnoides 1* 4* 3* 1* 1* a Tetraplodon brvoides 2* 2* 2* 9* 2* b Splaclnium sphiericuni 3* 3* »,::•• «>* »)# b vasculosuni 3* 3* 3* 3* 0* Funaria livgrometrica 3* 3* 3* 3* 3* Leptobryum pvriforme 4* 4* 2* 3* 4* Anoniobrvum filiforme . 2 1 2 3* V con ci mi urn 1 b Plagiobrvum Zierii 9 1 1 2 9* a demissum I* a Pohlia acuminata 1* 9* a polvmorpha 1 u cruda 4* 4* 4* 4* 4* u nutans 1* 1* 3* 1* 9* a cucullata 1* 2* a Ludwigii 1* a commutata 4* 4* 4* 4* 4* b gracilis 4* 4* 4* 4* 4* b Rothii 1 b tenuifolia «> 0 1 b proligera •i b grandiflora 2 b Mniobrvum albicans . 4* 4* 4* 4 4* b Bryum purpurascens 2* 3* 2* IT)* 1 b lacustre 2* 3* 1* 9* 0* a Kauri ni 1* a archangelicum 1* 1* 1* u inclinatum 4* 4* 4* 4* 4* a retusum 2* 1* Icel — islandicum. 1* THE BRYOPHYTA OF ICELAND 651 Table IV. The Frequency of the Species in the different Districts of Iceland (continued). E. Icel. N. X\V. W. S. Icel. Icel. Icel. Icel. 1) Bryum calophyllum u uliginosum Icel. Groenlundii b fallax a (cneum m bimuni b affinc b cirratum u intermedium 1) pallescens a subrotundum u capillare u caespiticium a comensc u argcntcum a neodamense var. ovatum b Duvalii u pallens u vcntricosum a arcticum u pendulum a Brownii a Jorgensenii m Mni um hornum a orthorrhynchum m serratum u spinosum m undulatum m cuspidatum b medium u affine u Seligeri m stellare b cinclidioides u punctatum b subglobosum b Cinclidium stygium b Paludella squarrosa b Amblyodon dealbatus b Meesea tricboides u triquetra b Catoscopium nigritum a Conostomum boreale . 2 1* 3* 2* 3* 1 3 1 4* 3 4* 3* 3 4 1 4 3 1 4 4* 4* 4 4* 3 4* 3* 1* 1 3* 2* 1* 3* 1 «)* 1 3 4* 3 4* 3* 1* 1* 2 4 1* 1 1 4 2 1* 4 4* 2* 4* 4 1* 4* 3 4* 3* 3 4 3 4* 3* 3 4 4 4* 3* 3 4* 2 2* 4* 1* 1* 3* o* 4 3* 4* 3* 1* 1* 3 4 2* 4 2 1 4 4* 1* 3* 3 4* 2 4* 3* * 1* 4* 1* 2* 1* 4 4* 4* 2* 2* 1* 4 4 3* 3 1 4 4 1 4 4* 1 3* 2 2* 3* 42 ' 652 A. HESSELBO Table IV. The Frequency of the Species in the different Districts of Iceland (continued). E. Icel. N. Icel. NW. Icel. W. Icel. S. Icel. u Aulacomnium palustre a turgidum u Bartramia ityplwlla b Plagiopus CEderi u Philonotis fontana b Arnellii a seriata b tomentella a Timmia norvegica b austriaca m Catharinea undulata a Oligotrichum hercynicum a Psilopilum Isevigatum m Pogonatum polytrichoides a dentatum var. minus . . . u urnigerum n Polytrichum alpinum m formosum b gracile a sexangulare u piliferum u juniperinum b strictum u commune b Swartzii b var. nigrescens u Diphyscium sessile u Fontinalis antipyretica Icel. islandica Icel. longifolia Icel. thulensis b androgyna m Leucodon sciuroides u Antitrichia curtipendula m Neckera complanata b Myurella julacea b apiculata 1) Leskea nervosa u catenulata m Anomodon viticulosus u Pterigynandrum filiforme a Lescuriea decipiens a radicosa . . . . . 4 2 4* 1* 2 4* 1 4 2* 2* 3* 3* 4* 9 1* 3* 2 2 3 3 1 1 2 3 1 4 1 4 2 4* 1* 4* 1 3* 4* 1 4* 1* 2* 3* 3* 4* 3* 3* 2* 3* 3 2 1* 3 4 3 4 1 4 2 4* 4* 4* 4* 3* 3* 4* 3* 4* 2* 3* 3 2 1 1 2 3 2 4 3 4 1 4 1 4* 4* 1 2 4* 4 3* 2* 3* 2* 1* 3* 4* 1 3* 3* 2* 3* 2 2* 3* 3 1* 1 3 1 4 3 4 1 4* 4* 1 1 4* 1 4 4* 3* 3* 2* 3* 4* 3* 3* 2* 3* 2 2 3* 3 2* 1 1* 2* 3 2 4 2 1 1 4 THE BRYOPHYTA OF ICELAND 653 Table IV. The Frequency of the Species in the different Districts of Iceland (continued). E. Icel. N. NW. W. Icel. Icel. Icel. S. Icel. b Lescunea filamentosa a Breidleri b patens b Heterocladium squarrosulum m Thuidium tamarisciuum m delicatulum m Philiberti b lanatum a Orthothecium rufescens a intricatum a chryseum m Cylindrothecium concinnum u Climacium dendroides m Isothecium myurum b tenuinervc u Homalothecium sericeum ... m Camptothecium lutescens b nitens u Brachythecium Mildeanum u salebrosum a collinum Icel. longifolium u populeum u velutinum a glaciale b reflexum u glareosum u albicans b erythrorrhizon b rivulare . b latifolium m Scleropodium purum m Eurhynchium strigosum m var. pnecox . . a diversifolium a cirrosum m piliferum m Swartzii in Stockesii m Rhynchostegium murale m rusciforme b v. atlanticum m Thamnium alopecurum 3 1 1 1 4 4* 1 4 2 4* 1 2 3* 1 3 3 2 1* 1 1 4 1 4 4 2 4* 1 3* 1 3 1 4 1 1 1 1 2 4* 3 2* 1 2* 2 4 1 4 2 4* 1 3* 3 4 3 2 1 2 1 2* 1 2 4 1 3 4 3 4* 1 2 1 1 3* 1 3 1 4 1 1 1 2 2 1 1 3 1 1 1 3 3 3 1* 1 4 2 3 4* 3 3* 1* 1* 2* 3* 3 4 3 1 3 3 2 1* 3* 2 3 654 A. HESSELBO Table IV. The Frequency of the Species in the different Districts of Iceland (continued). E. Icel. N. Icel. NW. W. Icel. Icel. S. Icel. u Plagiothecium silvaticum , u Rdcseanum u denticulatum b pulchellum m depressum m elegans a Amblystegium Sprucei m fluviatile m serpens m Juratzkanum b littorale , b compactum b salinum , m trichopodium m Hypnum Sommerfeltii u chrysopbyllum u protensum u stellatum b polygamum , u intermedium b revolvens u uncinatum m Sendtneri b Kneiffii u exannulatum a var. Rotae, u fluitans a var. falcatum . . u filicinum a curvicaule b decipiens m commutatum b falcatum m molluscum b imponens a Bambergeri a revolutum . . u cupressiforme a hamulosum a callichroum u Lindbergii u palustre a arcticum . 3 3* 1 2 4* 4* 9 4* 4* 3 4* 2 4* 2* 4 2 4* 1 1 4 2 1 1 4 1* 1 3 2 3* 1* 1* 1 1 1 1 1 4* 4* 3 4* 4* 1 3* 4* 1 3* 4* 2 4* 4 2 4 2* 3 1 3* 3 1* 4* 3* 9 4* 4* 2 4* 1 2* 4* 2 4 4 1 3* 4 1* 3 1 3* 1 1 1 2 4* 4* 9 4* 4* 2 4* 1 4* 1 1 2 4 3 1 1 4 3 2 2 4 2* 1* 1 3 1 3* 1 1 3 1 1* 1* 1 1 1 1 4* 3* 9 4* 4* 2 3* 1 4* 3* 4* 4* 4* 4* 2 3 4 3* THE BRYOPHYTA OF ICELAND 655 Table IV. The Frequency of the Species in the different Districts of Iceland (continued). E. Icel. X. Icel. NW. Icel. W. Icel. S. Icel. a Hvpnum alpestre 3* 3* 3* 2* 2* a alpinum 1* 3* 3* a ochraceum 4 4 4 4 4 u cord i folium 1 1* b Richardsonii 2* 2* 1 1 1 b giganteum 4* 4* 4* 4* 4* u stramineum 4 4* A 4 4 a sarrnentosum 3 3* 3* 3 3 b trifarium 1 1 a turgescens 1 1 1 u Acrocladium cuspidatum 4* 4* 4* 4* 4* u Scorpidium scorpioides 4 4 4 4 3 u Hvlocomium proliferum . 4 4 4 4 4 b pvrenaicum 1 11 parietinum 2 3 3 3 u loreum 2 3 3* u triquetrum 2 1 2 3 3 u squarrosum 4 4 4 4 4 b rugosum 3 3 3 3 3 Of the 93 Hepaticse, 20 Sphagna and 326 Musci veri found in Iceland, 7 Hepatica?, 3 Sphagna and 4 Musci veri (besides 3 varieties) have been found only on warm soil. The other 425 species (87 Hepaticae, 17 Sphagna and 322 Musci veri) enumerated in the above table can be arranged according to frequency in the following groups (Table V): — a. Dominant or very common species, the frequency of which is expressed by the figure 4 in all parts of Iceland or by 3 in only a few parts. b. Frequent species, the frequency of which is expressed by the figure 3 in the whole, or at any rate in the greater part, of Iceland. c. Species of which the frequency is expressed by the figures 1 a 2, or which have a higher degree of frequency only in a single district of Iceland. 656 A. HESSELBO Table V. Group a Group b Group c Hepaticie 23 14 49 Sphagna 1 3 13 Musci veri 64 82 176 Total . . . 88 20.7 o/0 99 23.5 o/o 238 55.8 o/o Iceland, according to the climatic conditions, may he divided into 5 districts, which division, also as regards the Land vegetation, coincides well with that employed by Helgi Jonsson (1912, p. 5) for the Marine vegetation along the coasts. East Iceland, from Eystri Horn in the South-east to Langa- nes in the North east. North Iceland, from Langanes to Cape Horn in the North- west. North-west Iceland, from Cape Horn to Latrabjarg. West Iceland, from Latrabjarg to Reykjanes. South Iceland, from the western point of the peninsula of Reykjanes to Eystri Horn. The boundary lines between these districts are in most places formed by ridges or high-lying mountain plateaus. In the South- east, Lonsheidi (height about 400 metres) and Hofsjokul form the boundary between South and East Iceland. West Iceland is sepa- rated from South Iceland by the mountain-chain which stretches «/ throughout the peninsula of Reykjanes, the lofty mountain of Hengill, the lake of Thingvalla and the mountains situated north of a line drawn from Thingvellir to Geysir. Between North and East Iceland there is no sharp boundary line, either as regards climate or geo- graphy. South-east Iceland (from Seydisfjordur southwards) has a very damp climate with many foggy days (near Berufjordur on an average 171 annually), while the western part of North Iceland (the districts about Eyjafjordur, Skagafjordur and Hunafloi) has a greater difference between the summer and the winter temperature, con- siderably less precipitation and comparatively few foggy days. North- west Iceland, which comprises the country around the deep, narrow THE BRYOPHYTA OF ICELAND 657 fjords which open out towards the north-west, lies rather isolated, separated as it is from North and West Iceland by Jokulls and lofty mountain-ridges. The boundary between North and West Ice- land is rather undefined. Several species which are common in West Iceland, but rare in or absent from North Iceland, are met with right in around Hunafloi. Here the range of hills east of Blondudalur appears to form a natural boundary, since Campto- theciam hitescens and Rhacomitrium heterostichum, for instance, have not been found east of this line, whilst other species common in North Iceland, for instance Orthothecium chryseum, Hypnum dedpiens and Thuidium lanatum, are rare west of it. Of the 87 Hepaticse, 17 Sphagna and 322 Musci veri enumerated in Table II, 30 Hepaticse, 4 Sphagna and 108 Musci veri (or col- lectively 33 0/o), are almost equally frequent in all the districts of Iceland, the frequency being (with a few exceptions) 3 — 4. The rest of the species can be grouped as follows: 1. Species with a mainly Southern distribution. 2. » Northern and Eastern distribution. 3. Western distribution. 4. Species which occur sporadically in several of the districts of Iceland. 1. Species with a mainly Southern Distribution. a. Found only in South Iceland (the figure denotes frequency). Meridional. Scleropodium purum 3 Eurhynchium Swartzii 3 Reboulia hemisphaenca 3 _. „ Stockesn 2 Fegatella comca 4 _, „ TA *• • Rhvnchostegium murale 1 Fossombroma Dumortieri 1 „, " . ., . , lx.~j Plagiothecmm elegans 1 Aneura multifida 1 T . ,, ,. depressum 1 Jamesoniella autumnalis 1 Lophozia excisa 1 ., Boreal. Lophocolea cuspidata 1 Lepidozia setacea 1 Haplo/Ja riparia 3 Weisia viridula 1 Sphagnum compactum 1 Tortula muralis 1 Pohlia grandiflora 2 mucronifolia 1 Amblystegium salinum 1 Hedwigia albicans 1 Hylocomium pyrenaicum 1 Orthotrichum anomalum 1 saxatile 1 Alpine. cupulatum 1 Scapania Bartlingii 1 Mnium undulatum 3 Dicranum fulvcllum. ..,.._..... 3 Anomodon viticulosus 1 Bryoxiphium norvcgicum 3 Thuidium tamariscinum . 3 Tortula obtusifolia. 1 658 A. HESSELBO Anomobryum concinnum 1 Bryum Jorgensenii 1 Ubiquists. Brachylhccium populeum 1 velutinum . 1 Icelandic species. Brachythecium longipilum 1 Fontinalis thulensis 1 longifolia 2 b. Found in South Iceland and in the most nearly adjacent parts of West and East Iceland. Meri'dio nal. s. w. E. Marsupella Funckii 1 1 Frullania fragilifolia .... 1 1 Lejeunea serpyllifolia .. . . 3 1 Sphagnum papillosum ... 2 2 Weissia crispata 1 1 Barbula unguiculata var. cuspidata 1 1 Trichostomum littorale . . 1 1 Leucodon sciuroides .... 2 1 Isothecium myurum 2 1 Eurhynchium piliferum . . 3 2 c. Most frequent in South Iceland, s. w. NW. N. E. Meridional. Radula complnnata .33 13 Madotheca Cordreana 4 3 Barbula cylindrica . . 3 1 Mnium hornum .... 4 serratum .... 3 2 Catharinca undulata. 4 3 Neckera complanata. 2 1 Thuidium delicatulum 321 Rhynchoslegium rus- ciforme 3 2 1 1 Thamnium alopccu- rum 3 1 Hypnum commutatum 32222 Boreal. Sphagnum medium. .211 Hymenostylium cur- virostre 31 1 s. w. E, Hypnum molluscum .... 4 3 1 Thuidium Philiberti. 3 1 Boreal. Fontinalis androgyna. . , Alpine. Dicranum Andersonii . . Ubiquists. Grimmia patens 1 1 2 2 1 3223 1 1 2 rarer in the other districts of Iceland. s. w. NW. N. E. Grimmia torquata... 43212 Plagiobryum Zierii.. 22112 Alpine. Bryum anieum 3 1 1 1 2 Ubiquists. Sphagnum subnitens. 221 Bryum capillare .... 2 1 pendulum ... 2 1 Mnium Seligeri 4 2 1 1 1 2 3 Antitrichia curtipen- dula . . 3 3 2 2 2 Hypnum palustre... 32 21 cupressiforme 43 22 Hylocomium loreum. 3 3 2 triquetrum 33212 2. Species with a mainly Northern Distribution. With the exception of the southernmost part of East Iceland almost as far as Djupivogur and the westernmost part of North Iceland — as far as Blondudalur — there is a very great ? THE BRYOPHYTA OF ICELAND 659 resemblance between the Bryophyte vegetation of East and North Iceland, therefore they will partially be mentioned collectively in the following lists. a. Found only Mcrid ional. Sphagnum angustifolium 1 Leptodontium flcxifolium 1 Amblystegium trichopodium . . . . 1 Boreal. Mnium spinosum Amblyodon dealbatus.. . . Brachvthecium latifolium in North Iceland. Alpine. Sauteria alpina 1 Scapania remota 1 Wei si a Wimmeriana . 1 1 1 Haplozia pumila Ponlia proligera Rothii 1 Brvum fallax. 1 1 1 1 Dicranoweisia compacta . . . Pottia latifolia Desmatodon cernuus Bryum comensc Pohlia Ludwigii Eurhynchium diversi folium 1 1 1 1 1 1 Lescurrea rigescens 1 Icelandic. Bryum islandicum 1 b. Found only in East Iceland. Meridional. Brvum bimum Boreal. Leptoscyphus anomalus 1 Bryum calophyllum 1 Alpine. Ditrichum nivale . Bryum neodamense var. ova turn Kaurini Grimmia incurva . Ubiquists. Cynodontium polycarpum Tortella inclinata . Icelandic. 1 Fontinalis islandica . 1 1 1 1 1 c. Found only in North and East Iceland. N. E. Meridional. Diplophyllum obtusifolium . . 1 1 Boreal. Schistidium confertum 2 1 Grimmia ovata . 2 2 Plagiopus (Ederi. , Hypnum trifarium Alpine. Orthotrichum Killiasii N. E. 1 1 1 1 1 1 d. Most widely distributed in East and North Iceland. E. N. NW. W. S E. N. NW.W. S. Boreal. Pohlia tenuifolia 22 1 Dicranum congestum . . 44 ? 3 2 Bryum purpurascens . . 23221 Distichium inclinatum . 121 lacustre 23122 Dissodon splachnoides. 14311 Paludella squarrosa. . . 44332 600 A. HESSELBO E. X. XW.W. S. E. N. NW.W. S. Cinclidium stygium ...44333 Alpine. Thuidium lanatum .... 4 4 2 2 1 Aulacomnium turgidurn 22211 Orthothecium chryseum 4422 Hypnum decipiens . . . . 44 1 Ubiquists. Richardsonii .22 1 Meesea triquetra 33222 3. Species with a mainly Western Distribution. a. Found only in North-west Iceland. Boreal. Tortula aciphylla 1 Haplozia sphaerocarpa 1 Hypnum fluitans var. falcatum. . 2 Polytrichum Swartzii 1 var. nigrescens .... 1 Ubiquists. Marsupella aquatica 1 Alpine. Gymnocolea inflata 1 Gymnomitrium revolutum 1 Sphagnum Gravetii 1 Sphenolobus politus 1 riparium 3 Cephalozia ambigua 1 Leskea catenulata 1 b. Found only in West Iceland. Meridional. Pohlia polymorpha 1 Trematodon ambiguus 1 Pogonatum dentatum var. minus. 1 Polytrichum formosum 1 Pogonatum polytrichoides 2 Ubiquists. Fissidens decipiens 1 Alpine. Encalypta contorta 1 Plagiobryum demissum 1 c. Most widely distributed in North-west Iceland. E. N. NW.W. S. E. N. NW. W. S. Boreal. Philonotis seriata 23421 Lophozia Flcerckei 4 2 Oligotrichum hercyni- HarpanthusFlotowianus 1142 cum 2 2 4 2 3 Scapania uliginosa .... 1 3 Polytrichum sexangulare 32433 Dicranella squarrosa . . 22421 Lescursea Breidleri . . . . 123 1 Bryum cirratum 2 2 3 2 1 Ubiquists. Alpine. Dicranum majus 3 1 Pleuroclada albescens. . 33422 fuscescens. . . 41 Pohlia cucullata 12 Pohlia nutans 1 1 3 1 2 d. Most widely distributed in the western part of Iceland. E. X. NW.W. S. E. N. NW.W. S, Ubiquists. Dicranum elongatum . . 222 Dicranella cerviculata.. 122 Isothecium lenuinerve . 1 3 :i Boreal. Meridional. Dicranum Blyttii 1 1333 Camptothecium lutescens 2 2233 Barbula fallax. 1 1 THE BRYOPHYTA OF ICELAND (5(51 Table VI. Collective Survey of the Number of Species in the different Districts of Iceland. Plant-geographical character r n 1 ) 5 I i i tn '~ u QJ • — ~ 8 Frequency 1-2 3-4 1-2 3-4 1-2 3-4 1-2 3-4 ; £± 3 Found only in East Iceland 1 2 4 2 9 North Iceland 23 2 33 50 43 30 38 68 987 Found only in North Iceland 3 7 10 20 Found onlv in N. and E. Iceland 1 4 1 ft North-west Iceland 7 3 19 49 27 31 25 61 222 Found only in North-west Iceland 8 5 4 1 13 West Iceland 25 8 37 48 30 25 33 76 282 Found only in West Iceland 3 3 2 8 By comparing the Tables and Lists of species contained in the present section it is seen that: The Meridional species belong mainly to the southern part of Iceland, in the south-western part of which they arrive at their maximum, both as regards number and frequency, and from thence decrease in number and frequency towards north-west and east. In south-east Iceland there is a tolerably sharp limit for their distri- bution, whilst a great number of species are to be found but with decreasing frequency even throughout the whole of West Iceland. The respective percentages of the entire number of species are as follows: South Iceland 19 °/0; East Iceland 6%; North Iceland 9%; North-west Iceland 5% and West Iceland 12%. A comparatively great number of species have been found in a single locality, or in a few localities, in North Iceland, especially around Eyjafjordur and eastwards in the valleys towards Myvatn, which may probably be due to the higher summer temperature of these districts. 662 A. HESSELBO \ The Boreal Group, over the whole of Iceland — with the exception of South Iceland — constitutes the same percentage of the vegetation (S. Icel. 24 %; E. Icel. 30 %; N. Icel. 29 °/0; NW. Icel. 31 °/0 and W. Icel. 30 %), and the great majority of the species belong to those which are common everywhere (56 species are common to all the districts of Iceland, with a frequency of 3--4, corresponding to about 60-75 %). The Alpine Group likewise shows almost the same percent- age in all the districts (S. Icel. 23 %; E. Icel. 25 °/0; N. Icel. 26 %; NW. Icel. 26 % and W. Icel. 20 %) of which about half the number (some 30 species) are common to all the districts. The Ubiquitous Group comprises chiefly species which have a great distribution in all parts of Iceland (S. Icel. 34 %; E. Icel. 39 %; N. Icel. 38 %; NW. Icel. 39 °/0 and W. Icel. 38 %), 73 of which (67 — 85 %) are common to all the districts, with a frequency of 3-4. The composition of the vegetation as regards percentage is thus very nearly the same everywhere as regards the three last groups, whilst, with regard to the meridional species, the country may be divided into a north-eastern and a south-western part. The North-eastern part comprises East and North Iceland as far as Blondudalur. The meridional species play a very slight role in the vegetation here. Two species only, Met~geria fnrcata and Rhacomitrinm aciculare, are common everywhere in this part, and live species, viz. Radnla complanata, Madotheca Cordceana, Catha- rinea undnlata, Mniiim ho r mini and Hypmim commiitatnm, are some- what frequent in East Iceland, but are absent from, or are rare in, North Iceland. Some few, principally Boreal and Alpine species, are charac- teristic of North and East Iceland. Hijpmim decipiens is very common from Seydisfjordur to Blondu- dalur, but is absent from, or is rare in, the other parts of Iceland. Orthothecium chnjseum is one of the most commonly occurring species in the whole of East and North Iceland, but is absent from South Iceland, and is rather rare west of Hunafloi. Grimmia ovata has been found only in East and North Iceland. Philonotis tomentella is very common in meadow-ground in North and East Iceland, from Seydisfjordur; but is less frequent on damp rocks in other parts of Iceland. THE BRYOl'HYTA OF ICELAND 663 Cinclidium stygium, Meesea triquetra, Palndellasqnarrosa, Thnidiiim lanatnm, Hijpnnm exannnlatnm, H. Richardsonii, H. sarmentosum and H. alpestre occur far more abundantly in the northern half of Ice- land than in the southern, and are often the most abundant con- stituents of the vegetation. Dicranum congestnm, which is one of the most commonly oc- curring species in North and East Iceland and occur there in numerous forms, is far more rare in South and West Iceland, and is evidently absent from North-west Iceland. •j A rather considerable number of species, which are most fre- quent in South and West Iceland, decrease in frequency throughout East Iceland, and are absent from, or are rarer in, North Iceland, for instance Scapania dentata, Anoectangium compactum, Grimmia torquata, Rhacomitrinm heterostichum, R. fascicnlare, Amphidinm Mon- geottii, Mnium Seligeri, Diphyscium sessile, Hijpmun filicinum, H. cn- pressiforme, Hylocomium parietinum and H. triqnetrum. South Iceland. The vegetation is primarily characterized by the presence of numerous meridional species, of which those with a frequency of 3 — 4 constitute an essential part of the moss- • covering. Fegatella conica and Rebonlia hemisphcerica in company with Preissia commntata and Marchantia polymorpha form special Mar- c/?a/i/zaceo?-associations on damp shady tuff-faces. Lejeunea cavifolia, Madotheca Cardoeana, Barbula cylindrica, Mnium serratnm, M. nndn- latum, Catharinea nndnlata, Thnidiiim tamariscinnm, T. delicatulum, T. Philibertii, Eurhynchium piliferum, E. Swartzii, Rhynchosteginm rnsciforme , Scleropodinm pnrnm, Thamninm alopecnnim, Hijpmim mollnscnm and H. commntatnm are the most frequently occurring species in SW. Iceland. Of the boreal Bryophyta Haploiia riparia, Hymenostylinm cnruiroslre, Grimmia torqnata and Plagiobrynm Zierii are most widely distributed in South Iceland; but this is no doubt chiefly due to the fact that a suitable substratum (tuff) abounds. The Alpine species Dicranum Andcrsonii, D. fill vellum and Bry- oxiphhim norvegicnm are common in the tuff districts of South Ice- land, but have not been found in other parts of the country. Several ubiquists occur more frequently and abundantly in South Iceland than in the other districts, for instance Mninm Seligeri, Anti- trichia curtipendiila, Hypnnm palnstre, H. cnpressiforme, Hylocomium lorenm, H. triqnetrnm and H. parietinum. These species ascend only exceptionally above the limit of the birch. (564 A. HESSELBO The difference in the climate is also apparent from the fact that species, which in North and East Iceland are common as far down as the low land, in South Iceland are first met with in abundance at a higher altitude. This is for instance the case with Schistidinm rivulare, Oncophorus Wahlenbergii, 0. virens and Dicra- nnm congestnm which are not common until at a height of 200- 300 metres. The Bryophyte vegetation in the higher-lying bogs (200 -500 metres) also corresponds closely with the bog vegetation of the lowlands of North and East Iceland, while the bog vegeta- tion of South Iceland differs somewhat considerably in character (p. -)61). North-west Iceland. The Bryophyte vegetation differs in several points from that of the other districts. From a narrow belt of coastal land the country rises abruptly to a height of about 500 metres, so that there is only room for the boggy tracts, so common in the other districts of Iceland, in those valleys which, from the head of the fjords, ascend towards the high land. Here the number of species is essentially smaller than in the other districts of Ice- land, since many of the common species, as well as of the rare ones, are absent, on the other hand, however, there are some few7 species which are widely distributed in North-west Iceland, but are absent from, or rarer in the other districts. This, among others, is the case with regard to several of the species belonging to the heath formation. Dicramim fuscescens, D. majus and D. molle are very common in NW. Iceland and, in association with other species (especially Hepaticse), form Dicramim heaths (p. 591): a formation which is otherwise rare in Iceland. Pohlia nntans and Bryum cirratum are also common, especially in the birch coppices. Polytrichum piliferum is tolerably frequent and has been found in fruit in several places. Lophozia Flcerkei is very common as far upwards as about 5(J() metres above sea-level. It has, however, only been found in a lava-field in SW. Iceland. There are also several hygrophilous species which are charac- teristic of NW. Iceland: Sphagnum squarrosum is frequent on damp slopes and S. riparium is rather common in pools. On inundated ground Scapania nliginosa, S. paludosa, Harpanthns Flotowianus and Philonotis seriata are very common and often form either sepa- rately or collectively the bulk of the vegetation. Hypnnm fluitans var. falcatum occurred abundantly north of Isafjordur. THE BHYOPHYTA OF ICELAND 665 The rocky flat is very widely extended in NW. Iceland, since it comprises all the flats and plateaus above the mountain slopes, and on the north side of the mountains descends as far downwards as to the sea-level. Several rocky-flat plants are therefore more widely distributed here than in the other districts of Iceland. Oliyo- trichnm hercynicnm, Rhacomitrinm sndeticiim, Conostomuin boreale, Lescurcea Breidleri, Gymnomitriiim concinnatum and Pleuroclada al- bescens are very common. Sphenolobns politus, Haplozia sphcero- carpa, Gymnomitriiim revolutum and G. varians have been found only on the rocky flats of NW. Iceland. Lescurcea filamentosa is very common and found fruiting on detached blocks and on rocks, and L. patens is also frequent and likewise sets fruit. Some few species, which are widely distributed elsewhere in Iceland, are absent here, for instance Scapania dentata, Radula com- planata, Gymnostomum rupestre, Campylopns Schimperi, Scelania c&sia, Mnium Seligeri, Hypnnm ciipressiforme and Hypmim palustre, whilst others are rare, for instance Preissia commntata, Leptobryiim pyri- forme, Catoscopium nigritum, Timmia austriaca and Hypnum falcatum. • The comparatively abundant occurrence of species of Sphagnum, and the lesser frequency of the last-mentioned lime-loving species, appear to indicate that the soil here is less calcareous than in the other districts of Iceland. The Bryophyte vegetation of NW. Iceland has, on the whole, a more decidedly xerophilous and Arctic character than that of the rest of Iceland. West Iceland has, with the exception of the southern part as far as Borgarfjordur, been very superficially investigated and, apart from a few scattered collections made by Helgi Jonsson, especially in Budahraun on Snaafellsnes, and my own collections near Stykkisholmur, the whole stretch of coast norlh of Hvalfjordur and around Breidifjordur is, from a bryological point of view, quite unknowrn. Several of the species characteristic of South Iceland occur here also, partially decreasing in frequency throughout West Iceland, for instance Thuidium delicatulum, Hylocomium loreum, Eiirhynchium piliferum and (in the South-west) Madotheca Cordceana. Some species have a decidedly westerly distribution in Iceland, being of almost equal frequency in West and South-west Iceland and a few also in The Botany of Iceland. Vol. I, part II. 43 666 A. HESSELBO : THE BRYOPHYTA OF ICELAND the North-west, whilst they are absent from, or rare in, the other districts of the country. To this group belong: Dicranella cerviculata, Dicranum Blyttii, D. elongatum (western part of N. Iceland around Hunafloi; NW. and W. Iceland), Ditrichum homomallum (common in the South-west), Isothedum tenuinerve, Rhynchostegium rusciforme, Hypnum hamiilosum and Hylocomium parietinum. Finally, Diplo- phyllnm albicans is characteristic of all the lava-fields of West and South-west Iceland. BIBLIOGRAPHY. As to the older records respecting the Flora of Iceland (Zoega, Gliemann, Hooker, Hjaltalin, Vahl, Hornemann, Lindsay, Caroll and others) reference may he made to the full mention of these authors hy Gronlund in Botan. Tidsskr., Vol. 4, 1870-71, p. 147 and Vol. 7 (2. R.. 3. Bd.), 1873, p. 1. Arnell, H. W. (1892), Lebermoosstudien im nordlichen Norwegen. Jonkoping. Arnell, H. W. and Jensen, C. (1907), Die Moose des Sarekgebietes. Naturw. Unters. des Sarekgebietes in Schwed.-Lappland, III, Stockholm. Braithwaite, The British Moss-Flora. London, vol. I, 1880-1887; vol. II, 1888 -1895; vol. Ill, 1903-09. Flora danica. Icones plantarum in regnis Daniae et Norvegiae nascentium ad illustrandam Floram danicam ediderunt G. C. Oeder, O. F. Miiller, M. Vahl, J. W. Hornemann. S. Drejer, F. M. Liebmann, Job. Lange, Fasc. 1 — 50. Hafniae, 1761 -1880. Gronlund, Chr. (1870-71), Bidrag til Oplysning om Islands Flora. Bot. Tidsskr.. Bd. 4, pp. 147—172. (1873), Bidrag til Oplysning om Islands Flora. 2. Hepaticae og Musci. Bot. Tidsskr., Bd. 7, pp. 1—26. — (1877), Islandske Naturforhold med sserligt Hensyn til Mosvsextens Betydning for Landskabet. Tidsskr. for populsere Fremst. af Naturvidensk.. 5 R.. IV, pp. 321—356. — (1881), Islands Flora. Kjobenhavn. (1884), Karakteristik af Plantevaexten paa Island sammenlignet med Floraen i flere andre Lande. Den Naturhistoriske Forenings Festskrift, Nr. 1, Kjoben- havn, pp. 107 — 145. — (1885), Afsluttende Bidrag til Oprysning om Islands Flora, Musci, Hepaticae. Lichenes. Bot. Tidsskr. XIV, pp. 159—217. (1895), Tillseg til Islands Kryptogamflora, indeholdende Lichenes. Hepaticae og Musci. Bot. Tidsskr. XX, pp. 90—115. Hagen. I. (1899 — 1901), Musci Norwegiae Borealis. Tromso Museums Aarshefter 21—22. Forarbejder til en norsk Lovmosflora I — XX. Det Kgl. Norske Videnskabers Selskabs Skrifter, Trondhjem 1908—1915. Jensen, C. (1897), Beretning om en Rejse til Fseroerne i 1896. Bot. Tidsskr. XXI. pp. 157—219. (1901), Br3rophyta. Botany of the Faeroes, vol. 1, Copenhagen, pp. 120 — 197. (1915), Danmarks Mosser. I. Hepaticales. Anthocerotales, Sphagnales. Koben- havn og Kristiania. Jonsson, Helgi (1895\ Studier over 0st- Islands Vegetation. Bot. Tidsskr. XX, pp. 17—89. (1899). Floraen paa Snaefellsnes og Omegn. Bot. Tidsskr. XXII. pp. 169—207. 43* 668 BIBLIOGRAPHY Jons son, Helgi (1900), Vegetationen paa Snsefellsnes. Vidensk. Medd. fra den Naturhist. Forening i Kjebenhavn, pp. 15 — 97. (1905), Vegetationen i Sydisland. Bot. Tidsskr. XXVII, pp. 1—82. (1912), The Marine Algal Vegetation. The Botany of Iceland, Part 1, 2. Copen- hagen and London. Limpricht, K. G., Die Laubmoose in Rabenhorst Kryptogamenflora von Deutsch- land, Oesterreich und der Schweiz. Leipzig 1890 — 1904. Loeske, Leopold (1905 — 6), Kritische Bemerkungen tiber einige Formen von Philonotis. • Hedwigia, Bd. 45, p. 100. (1905 — 6), Kritische Ubersicht der europaischen Philonotis- Arten. Hedwigia, Bd. 45, p. 145. 01911), Revision einiger Ambrystegium aus dem Herbare Limpricht. Ung. botan. Blatter, pp. 272—97. M tiller. K., Die Lebermoose in Rabenhorsts Kryptogamenflora von Deutsohland, Oesterreich und der Schweiz. Leipzig 1909 — 1915. Ostenfeld, C. H. (1899), Skildringer af Vegetationen paa Island. Bot. Tidsskr. XXII, pp. 227—253. Stefansson, St. (1896), Bemserkninger til Chr. Gronlimd: Tillseg til Islands Kryp- togamflora indeholdende Lichenes, Musci, Hepaticae. Bot. Tidsskr. XX, pp. 399 —402. Thorodsson, Th. (1914), An Account of the Physical Geography of Iceland, with Special Reference to the Plant-Life. The Botany of Iceland. Part I, 2. Copen- hagen and London. Warming, Eug. (1884), Om Gronlands Vegetation. Medd. om Gronland, XII, 245 pp. (1895), Plantesamfund. Grundtrsek af den okologiske Plantegeografi. Kjobenhavn. Warnstorff, C., Kryptogamenflora der Mark Brandenburg, Bd. I, Moose. 1901 -1903. Winther (1910), Beitrage zur Kentniss der Pohlia commutata, P. gracilis, P. cu- cullata und P. carinata. Hedwigia 49, p. 54. LIST OF THE SPECIES. Acrocladium cuspidatum (L.) Lindb. 541. Alicidaria geoscypha De Not. 409. - scalaris (Schrad.) Corda 408. Amblyodon dealbatus (Dicks.) P. B. 491. Amblystegium adunciun (L.) Lindb. 531. - chrysophyllum (Brid.) Lindb. 530. — cordifolium (vHedw.) de Not. 539. - compact nut (C. M.) Br. eur. 527. — curi'iccnde Dicks, et James. 534. — exannulatum de Not. 532. — filicimiHi (L.) de Not. 533. - fl-uitans (L.) de Not. 533. - flu fiat He (Sw.) Br. eur. 526. — giganteum de Not. 540. — ylaucum (Lam.) Lindb. 534. — fi, decipiens Lindb. 534. Intermedium Lindb. 531. — Juratzkanum Scbimp. 526. Kneiffii Br. eur. 532. - littorale (C. Jens.) Hsb. 526. — molle fi, alpinum Lindb. 538. ochraceum Lindb. 539. palustre (Huds.) Lindb. 538. polygamum Br. eur. 530. — prof ens um Lindb. 530. — revolvens de Not. 531. Richardsonii Lindb. 540. r'n'ulare (Sw.) Lindb. 538. - sarmentosum de Not. 541. - scorpioides (L.) Lindb. 542. — salinum Bryhn. 528. Sendtneri (Schimp.) de Not. 531. — serpens (L.) Br. eur. 526. — var. littoral-is C. Jens. 526. - Sm-ithii (Sw.) Lindb. 538. — Sprucei (Bruch) Br. eur. 526. stellatum Lindb. 530. — stramineum de Not. 540. — trichopodium (Schultz) Br. eur. 528. - trifarium de Not. 541. - turgescens Lindb. 541. Amphidium lapponicum (Hedw.) Scbimp. 463. Mougeottii (Br. eur.) Scbimp. 463. Amtrcwa petroplilla Ehrh. 434. Aneura latifrons Lindb. 405. multlfida (Lindb.) Dum. 404. — pinguis (L.) Dum. 404. Anisothecium rrispum Lindb. 439. Anomobryum concinnum (Spr.) Lindb. 469. — filiforme (Dicks) Husnot. 469. Ancectangium Mougeottii Lindb. 463. — lapponicum Hedw. 463. Anomodon viticulosus (L.) H. et T. 510. Anthelia jidacea (L.) Dum. 423. — Juratzkana (Limpr.) Trevis. 423. nivalis (Sw.) Limpr. ex p. 423. Anthoceros punctatus L. 429. Antitrichia curtipendula (Hedw.) Brid. 509. Aongstrosmia longipes (Somf.) Br. eur. 437. Archidium phascoides Bridel. 434. Astroplnjllum cinclidioides (Blytt) Lindb. 490. - cuspidatum (L.) Lindb. 489. — liornum (L.) Lindb. 487. marginatum (Dicks.) Lindb. 487. — medium Lindb. 488. orthorrhynchum Lindb. 487. pseud op unctatum (B. S.) Lindb. 490. jtunctatuni (L.) Lindb. 490. Sdigeri Lindb. 489. - silvaticum Lindb. 488. - spinoxum Lindb. 488. - stellare Lindb. 490. — undulatum Lindb. 488. Aulacomnium palustre (L.) Schwagr. 493. - turyidum (Wahlb.) Lindb. 493. Barbula citrriroztris Lindb. 435. cylindrica (Tayl.) Scbimp. 454. fallax (Hedw.) 453. — var. Icevifolia n. sp. 453. 670 LIST OF THE SPECIES Barbula icmadopMla Schimp. 455. rubella (Hoffm.) Mitt. 451. ungmculata (Huds.) Hedw. 453. var. cuspidata Braith. 453. Bartramia itypnylla (Haller) Brid. 494. - (Ederi (Gunn.) Limpr. 494. Blasia pusilla L. 407. Blepharostoma trichophyllum (L.) Dum. 422. Blindia acuta (Huds.) Br. eur. 448. Brachythecium albicans (Neck.) Br. eur. 521. - cirrosum Schimp. 523. - collinum (Schleich.) Br. eur. 518. erythrorrhizon Br. eur. 521. - glaciate Br. eur. 520. glareosum (Bruch.) Br. eur. 521. - latifolium (Lindb.) Philib. 522. - longipilum n. sp. 518. — Mildeanum Schimp. 517. populewn (Hedw.) Br. eur. 520. — reflexum (Starcke) Br. eur. 520. - rivulare (Bruch) Br. eur. 521. — salelrosum (Hoffm.) Br. eur. 518. velutinum (L.) Br. eur. 520. Bryoxiphium norvegicum (Brid.) Mitten. 450. Bryum affine (Bruch) Lindb. 482. arcliangelicum Br. eur. 475. — arcticum (B. Br.) Br. eur. 486. - argenteum L. 485. bimum Schreb. 482. — Broicnii Br. eur. 487. - calophyllum B. Brown. 479. - ccipillare L. 484. cirratum Hoppe et Hornsch. 483. comense Schimp. 484. - cuspidatum Schimp. 482. ccespiticiiun L. 484. DuroUi Voit. 485. elegans N. v. Es. 484. - fallax Milde. 480. Gronlnndii n. sp. 479. inclinx#!fo)-nu' L. 536. - currirtnde Jur. 534. - cuspidatum L. 541. f fed pi ens (de Not.) 534. - erythrorrhizon Hartm. 521. - exdiiiiii/ftfmn (Gumb.) 532. var. purpttrascenft (Schimp.) 532. Rota: (de Not.) 532. • serri(in Schimp. 540. - ylaciale Hartm. 520. — glarcoxinn. Bruch. 521. - h((tn>niclliitort« Lindb. 466. - l/« (Wils.) Br. eur. 511. LesJcea eaten nli«trix (Schleich.) Evans. 414. barlxitn (Schmid.) Dum. 414. excisa Dicks.) Dum. 415. — Flcerckei (W. et M.) Schiffn. 413. - heterocolpos (Thed.) Howe. 416. — Hornschuchiana (Nees) Macoun. 416. Kunzeana (Hub.) Evans. 414. - hjcopodioides (Wallr.) Gogn. 412. — Mllller I (Nees) Dum. 416. • quadr'doba (Lindb.) Evans. 413. — quinquedentata (Huds.) Cogn. 412. — Schultzii (Nees) Schiffner. 416. rcntricosa (Dicks.) Dum. 414. Wenzelii (Nees) Steph. 415. inn/inn! Br. eur. 488. orthorrhynchum Brid. 487. — nnnrtdtnni (L.) Hedw. 490. • Seliger! Jur. 489. Schrad. 487. (Voit) Schwgr. 488. Reich. 490. — xnbi/1'ibnxmn Br. eur. 490. — Hndnlntuni (L.) Weiss. 488. Mollia frnyiU* (Drum.^ Lindb. 453. inclinntn (Hedw.) Lindb. 452. (Mitt.) 452. (L.) Schranck. 452. Mt/nri'1/r/ npiculata (Hiib.) Br. eur. 509. — jidacca (Will.) Br. eur. 509. fciterrinui (Brid.) Lindb. 509. rremilntn (Sm.) 409. - h!(.-fli<'<-iu.in rhryxeiun (Schwagr.) Br. eur. 515. - intricntum (Hartm.) Br. eur. 515. rnfexcenx (Dicks.) Br. eur. 515. Orthoti'ichum anontnlnni Hedw. 464. — IHi/ftii Schimp. 465. rnjn4. - si i. ni tile Schimp. 464. — Sfnnnii Hornsch. 4(>."). **n (L.) Brid. 491. (Gottsche) Limpr. 405. Jur. 496. Pellia Philonoti* 674 LIST OF THE SPECIES Philonotis Arnellii Husnot. 495. - fontana (L.) Brid. 494. - seriata (Mitt.) Lindb. 496. - tomentella Mol. 496. Plagiobrymn demissum (H. et H.) 470. Zierii (Dicks) Lindb. 469. Plagiochila asplenioides (L.) Dum. 417. Plagiopus (Ederi (Gunn.) Limpr. 494. Plagiofhecium denticulatum (L.) Br. eur. 525. - depression (Bruch) Dixon. 525. - elegans (Hook.) Sull. 525. - pulchellinn (Dicks.) Br. eur. 525. Rceseanum (Hampe) Br. eur. 524. - sili'iit'n-inn (Huds ) Br. eur. 524. var. Rccsei (Hampe) Lindb. 524. Phuroclada albescens (Hook.) Spruce. 420. Pleurozygodon cestivus (Hedw.) 435. Pogonatuni tiludo*a C. M. 425. LIST OF THF SPECIES 675 Scapania purpurascens (Hook.) Pcnrs. 425. — remota Kaalaas. 424. — subalpina N. ab Es. 424. idiginosa (Sw.) Dum. 425. undidata (L.) Dum. 426. Schist id turn alpicola (Sw.) Limpr. 458. — var. eualpicola Loeske. 458. - rivularis (Brid.) 458. - apocarpum Br. eur. 457. — — subsp. confertiun Funck) Loeske. 458. - gracile (Schwgr.) Loeske. 458. valgare (Chal.) Loeske 457. Scleropodlum punun (L.) Limpr. 522. Scorpidium scorpioides (L.) Limpr. 542. Sphagnum acutifolium Ehrh. 432. angustifollum C. Jensen. 433. — Austini Sull. 430. • compaction de Cand. 431. cymbi folium (Ehrh.) Hedw. 430. — Dusenii C Jens. 433. • fimbriatum Wils. 431. — Girgensohnii Russow. 431. — Gravetii Russow. 431. — imbricatum (Hornsch.) 430. — inundatum Russow. 430. — Lindbergii Sch. 433. medium Limpr. 430. — papillosuni Lindb. 430. rigidum Schimp. 431. — riparium Aongstr. 433. • rubellum Wils. 432. • Eussoicii Warnst. 432. — squarrosiini Crome. 431. • subnitens Russ. et Warnst. 432. — teres (Schimp.) Aongstr. 431. — Warnstorffii Rnssow 432. Sphenolobus minutus (Crantz) Steph. 411. • politus (Necs) Steph. 412. • saxicola (Schrad.) Steph. 412. Sphcerocephalus palustris (L.) Lindb. 493. — turgidus (Whlb.) Schwagr. 493. Splachnum peduncidatum (Huds. Lindb. 467. sphcericum (L.) Swartz. 467. — vasculosum L. 468. Stereodon arcuatux Lindb. 537. • Bambvrgeri (Schimp.) Lindb. 536. Stereodon callichrous Brid. 537. — chryseus (Schwagr. i Mitt. 515. Lindb. 536. (Hedw.) Brid. 535. - revoluttt* Mitten. 536. r it few us Dicks.) Mitt. 515. — subrufus (Wils.) Lindb. 515. ^"•artzia tnclinata Ehrh. 450. - montana (Lam.) Lindb. 450. Scelania ccesia (Vill.) Lindb. 449. Tayloria linyulata (Dicks.) Lindb. 467. Tetraplodon bnjoides (Zoega) Lindb. 467. - innioides (L.) Br. eur. 467. Thuidium abiethnun (L.) Br. eur. 514. — Blandou'ii (W. et M.) Br. eur. 515. - delicatulum (L.) Mitten. 514. - lanatttm (Strom) Hagen. 515. - Philiberti (Limpr.) 514. — tamariscinum (Hedw.) Br. eur. 514. Tinimia auxtriaca Hedw. 497. - norvegica Zett. 497. Tortella fragilis (Drumm.) Limpr. 453. inclinata (Hedw.) Limpr. 452. — tortuosa (L.) Limpr. 452. Tortula aciphylla (Br. eur.) Hartm. 457. — cernua (Hiibn.) Lindb. 455. — latifolia (Hedw.) Lindb. 455. — niucronifolia Schwagr. 456. - nturalis (L.) Hedw. 456. — norregica (Web.) Whlb. 457. — obtusifolia Schleich. 456. — ruralis (L.) Ehrh. 456. — subulata (L.) Hedw. 456. Trematodon ambiguus (Hedw.) Hornsch. 447. Trichostomum littorale Mitt. 452. Ulota maritima C. M. et Kindb. 463. — phyllantha Brid. 463. Webera annotina (L.) Lindb. 463. — bulbifera Warnst. 473. - sessttis Lindb. 507. WelsiO' crispata (Br. germ.) Jur. 436. inarititna Britt. 463. Wimmeriana (Sendtn.) Br. eur. 436. — nridula (L.) Hedw. 436. ERRATA. . P. 429 1. 7 add Gevsir! «/ - 434 - 1 should read "I. Musci veri1'. - 438 - 25 for "elongatum" read "elongatus". 463 - 10 from bottom for "Weissia" read "Weisia' 471 6 for "Wiinsted" read "Wiinstedt". - 473 - 24 for "fenuifolia" read "grandiflora". - 588 - 19 for "Associations" read "Formations". CONTENTS. Page Introduction 397 I List of The Bryophyta 402 I Hepaticje 402 II Sphagnales 430 III Musci veri 434 II The Bryophyte Communities 545 • I The Lowland Formations 546 The Littoral Br3'ophyte Vegetation 546 Hydrophilous Bryophyte Formations 547 The Bryophyte Vegetation of Running Water and of Lakes.... 54S The Bryophyte Vegetation of Inundated Gravelly Soil 550 The Bryophyte Vegetation of Muddy Soil near Springs (I)y) . . . 551 The Bryophyte Vegetation of Boggy Soil 555 The Bryophyte Vegetation of Damp Sandy Soil 564 The Bryophyte Vegetation near Hot Springs 565 Mesophilous Bryophyte Formations 584 Xerophilous Bryophyte Formations (Heaths) 588 The Bryophyte Vegetation of the Bocks 595 The Bryophyte Vegetation of the Tuff Rocks 604 The Bryophyte Vegetation of the Lava- fields 612 II The Bryophyte Vegetation of Mountain Heights 623 III The Components of the Bryophyte Flora 629 IV The Altitudinal Distribution of the Species 635 V The Horizontal Distribution of the Species 644 Bibliography 667 List of the Species 669 Errata . 676