282 Dansk Botanisk Arkiv, Bd. 3. Nr. 1. 



Specimens with tetrasporangia were found. The tetrasporangia 

 occur in the upper end of the branchlets with definite growth. 

 These grow thicker in the fertile part, the whole branchlet assuming 

 thereby a clavate appearance (Fig. 281). The tetrasporangia are 

 placed in screws, one in each segment. They are about 80 ;« in 

 diameter. The specimens with these organs were gathered in Ja- 

 nuary and February. 



As mentioned above this plant is gathered both in shallow 

 water and in deep water down to a depth of about 30 meters. 



It is a rather common species along ttie shores of the islands. 

 Geogr. Distrib. : Seems to occur in nearly all warm seas. 



Bryothamnion Kütz. 



1. Bryothamnion triquetrum (Gmel.) Howe. 



Howe, M. A., in Journal of the New York Bot. Garden, vol. XVI, 

 1915, p. 222. 



Bnjothamnion trianguläre Kütz., Spec. Alg., p. 842. J. Agardh, Spec. 

 Alg., vol. II, p. Ill, p. 850. Falkenberg, Rhodomelaceen, p. 172, tab. 19, 

 figs. 32—33. 



Fucus iriqueter S. G. Gmelin, Historia Fucoruni, 1768, p. 122, tab. 8, 

 fig. 4. 



Fucus triangularis J. F. Gmelin in Linné, Syst. Naturæ, Editio 13, p. 1383. 

 Turner, Fuci, tab. 33. 



Alsidium trianguläre J. Ag. in Linnæa, vol. XV, 1841, p. 28. Harvey, 

 W. H., Nereis Bor.-Am., Part II, p. 15, tab. XIII. A. 



As pointed out by Falkenberg it is rather difficult to ex- 

 tract the summit with the young growing point of this plant 

 from the surrounding branchlets which quite cover it, but after 

 some attempts I succeeded in removing one, of which the ac- 

 companying drawing is a copy. This agrees well with Falken- 

 berg's description. From the cup-shaped top-cell disc-formed seg- 

 ments are gradually cut off, which afterwards again are divided 

 by vertical walls. From every second segment a trichoblast is 

 developed. The trichoblasts are placed in a screw line with a diver- 

 gency of ^/s; in fig. 282 the uppermost tips of the trichoblast 

 marked 4 are seen only, as this trichoblast stands behind the 

 main axis and branch 5. 



The trichoblasts are rather poorly developed, only forked 

 once above the basal cell, and the two filaments, when fully devel- 

 oped, consist of 4 cells only; the nethermost cells are cylindrical — 

 barrelshaped, the uppermost short, subspherical ; the diameter of 



I 



