178 KJELLMAN, THE ALG OF THE ARCTIC SEA. 
Callithamnion arbuscula (Dutw.) Lynes. 
Hydr. Dan. 123. Conferva arbuscula Dituw. Brit. Conf. t. 85. 
Deser. Callithamnion arbuscula J. G. Ac. Epier. p. 37. 
hig. » » Harv. Phye. Brit. t. 274. 
Exsice. » » ArescH. Alg. Scand. exsice. N:o 14. 
Syn. Callithamnion arbuscula Kugen, Nordl. Alg. p. 21. 
Habitat. The present species grows litoral on exposed coasts, partly on rocks 
between tides, partly in rock-pools. Occurring often in great masses, it contributes 
essentially to mark the character of the vegetation. K1imen states that on the coast of 
Nordlanden it begins to appear at the beginning of July and develops tetrasporangia 
already in the same month, carpospores in August. It seems to follow from these 
statements that the species is annual here. On the coasts of Britain it is perennial 
according to Harvey, attaining its highest development during the summer and the 
autumn. 
Geogr. Distrib. Known only from the Atlantic region of the Polar Sea. 
Locality: The Norwegian Polar Sea: Nordlanden, common and plentiful. 
Callithamnion roseum (Roru) Harv. 
in Hook. Brit. Fl. 2, p. 341. Conferva rosea Rorn, Cat. Bot. 2, p. 182. 
Descr. Callithamnion roseum J. G. Ac. Epier. p. 39. 
Fig. » » Hary. Phye. Brit. t. 230. 
Syn. Callithamnion roseum Kieren, Nordl. Alg. p. 22. 
Habitat. It has been found by Kien in rock-pools between tide-marks. Taken 
with tetrasporangia in August. 
Geogr. Distrib. Like the preceding species, this is known only from the Atlantic 
region of the Polar Sea. 
Locality: The Norwegian Polar Sea: at Giver in Nordlanden, its most northerly 
place of growth. 
Callithamnion corymbosum (Sm.) Lynas. 
Hydr. Dan. p. 125. Conferva corymbosa Sm. Engl. Bot. t. 2352. 
Descr. Callithamnion corymbosum J. G. Ac. Epicr. p. 40. 
Fig. » » Harv. Phye. Brit. t. 272. 
Exzsice. » » ArescH. Alg. Scand. exsice. N:o 15. 
Syn. Callithamnion corymbosum KLEEN, Nord]. Alg. p. 21. 
Habitat. It grows scattered on exposed coasts, sublitoral, attached to old shells 
and deepwater alew, as Desmarestia aculeata, Ptilota pectinata a. o. It attains a consi- 
derable size even in the Polar Sea. Krneyn’s collections contain specimens of very luxu- 
riant growth and a height of even 6 cm. In the Polar Sea it has as yet been found 
only sterile. 
