190 KJELLMAN, THE ALG OF THE ARCTIC SEA. 
within the Laminariacew-formation. Most of the Greenland specimens are collected in 
March and April, some in October, which seems to indicate that the plant is to be 
found here all the year round. Judging from these specimens it also bears repro- 
ductive organs at different seasons. 
Geogr. Distrib. Its maximum of frequency is no doubt in Baffin Bay. Besides, it 
has been observed in the castern part of the Greenland Sea. The northernmost locality 
where it is at present known to grow, is Fairhaven, on the north-west coast of Spitz- 
bergen, Gat. N. 79°49. 
Localities: The Greenland Sea: the north-west coast of Spitzbergen, rare. 
Baffin Bay: Kakertok, Tessarmiut Bay, Kangek (near the same bay), Julianeshaab, 
Egedesminde, Godthaab. If the P. vulgaris of Croatn and Dick is the present species, 
as I think it is, D. minatum, is known also from Disco Bay and Whale Sound. 
Gen. Porphyra Ac. 
Syst. Alg. p. XXXII. 
Porphyra laciniata (Licutr.) Ag. 
]. c. p. 190. Ulva laciniata Ligutr. Fl. Scot. p. 974. 
f. typica. 
Descr. Porphyra laciniata Tuur. in Le Jol. Liste Alg. Cherb. p. 100—101. 
Fig. » » Harv. Phyc. Brit. t. 92. 
Exsicc. » » Arescu. Alg. Scand. exsicc. N:o 116. 
f. umbilicalis (L.) Kieren. 
Nordl. Alg. p. 23. Ulva umbilicalis L. Spec. Pl. 2, p. 1163. 
Descr. Wlva umbilicalis Lynes. Hydr. Dan. p. 28 
Exsicc. Porphyra laciniata f. b. Arescu. Alg. Scand. exsice. N:o 260. 
Syn. Porphyra laciniata Arescu. Phye. Scand. p. 404. 
» » Gost, Algenfl. Weiss. Meer. p. 50. 
» » Keen, Nordl. Alg. p. 23; exel. var. lineari et vulgari. 
» » umbilicata Rupr. Alg. Och. p. 393. 
» » vulgaris Nyl. et Sel. Herb. Mus. Fenn. p. 75. 
Ulva umbilicalis Gunn. Fl. Norv. 2, p. 121. 
J » » Wea. Fl. Lapp. p. 506; excel. var. 
Remark on the species. Tuurnr has pointed out that what is set down by algo- 
logical authors under the name of P. linearis, P. vulgaris or P. purpurea, and P. laci- 
niata, sometimes as separate species, sometimes as forms of the same species, is in fact 
nothing but one and the same plant at different stages of development; cp. Tuur. 1. ¢. 
This being so, the names P. linearis, vulgaris, and purpurea, ought to be struck out 
altogether. The plant described under the name of Ulva umbilicalis or U. umbilicata 
I think ought to be regarded as a special form of P. laciniata. It differs from the 
typical P. laciniata both biologically and morphologically, and is well known to Scandi- 
