KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 20. N:0 5. +) 
Geogr. Distr. The Atlantic region of the Polar sea. Within the arctic region it 
has not as yet been found. 
Locality. The Norwegian Polar Sea: Tromsé amt near the town of Tromsé, the 
only place where it is known to occur. Here it has been found by M. Fostie. 
Lithothamnion Norvegicum Aregscu. (nob). 
Descr. Lithothamnion caleareum var. norvegicum AregscH., Obs. Phyc. 3, p. 4—5. 
Fig. Lithothamnion norvegicum tab. nostra 5, fig. 9—10. 
Remark on the determination of the species. J. EK. ArescnouG |. c. has described, 
under the preceding combination of names, a plant from the southwest coast of Norway, 
that has also been found in the Polar Sea. On pl. 5, I have given figures of one 
specimen from the south of Norway (fig. 9) and of another from the Polar Sea (fig. 10). 
Judging from the fact that no overgrown sporangia are to be found on sections of 
older frondal portions, the plant with regard to the inner structure belongs to that 
group of Lithothamnia which possesses external conceptacles of sporangia. ARESCHOUG 
considers this plant to be a local form of Melobesia (Nullipora) calcarea Evi. et Sor., 
occurring on the coasts of England and figured by Harvey (Phyce. Brit.) and Jonnsron 
(Brit. Spong. Lith.) It is certainly possible that this may indeed be the case, but the 
statement of ArgescHouGe »forma M. calcarea quam depinxit et descripsit Harvey (est 
forsan maxima et magnopere evoluta) a nostra valde abhorrens» being clearly quite 
correct, and the Norwegian specimens being unlike those figures of Nullipora calcarea, 
much differing from one another and possibly designating different species, which 
Jounston gives, I consider myself entitled to regard the above-mentioned plant, found 
on the coast of Norway, as a distinct species separated from Melobesia valcarea Harvey 
and Nullipora calcarea JOHNSTON. 
Hab. It grows, spreading stratiformly, in 10—15 fathoms water. Cf. ArrscuouG 
1. c. Only sterile specimens are known. 
Geogr. Distr. This species belongs only to the Atlantic region of the Polar Sea, 
and seemingly only to its most southerly part. It has not been found to the north 
of Nordlanden. 
Locality. The Norwegian Polar Sea: Nordlanden at Lédingen (Fostie). 
Lithothamnion glaciale nob. 
L. fronde demum crustam formante validam circum lapides vel conchas effusam e roseo flavescentem, 
plus minus lobatam, ramos simplices, conicos, obtusos vel subeylindricos, usque 7—8 mm. altos, inferne dia- 
metro usque 5 mm., scabriusculos undique emittentem; conceptaculis sporangiferis demum innatis, minutis, con- 
vexiusculis at parum prominentibus, creberrimis, nullo ordine in crusta ramisque dispositis; sporangiis binas 
sporas foventibus, 80—135 w. longis, 40—60 w. crassis; Tab. 2 et 3. 
Syn. Lithothamnion caleareum Ksetum., Vinteralg. p. 64. 
» » KueeENn, Nord]. Alg. p. 11. 
» fasciculatum Arescu. Obs. Phye. 3, p. 5 (saltem ex parte). 
» » DickiE, Alg. Sutherl. 1, p. 142. (?) 
> » Gost, Algenfl. Weiss. Meer. p. 22. 
» » KJELLM. Spetsb. Thall. 1, p. 3, Algenv. Murm. Meer, p. 7 et alibi. 
