188 KJELLMAN, THE ALGvE OF THE ARCTIC SEA. 



Hahitat. Only a few speciraeiis have beeii fouiid within the sublitoi-al zone, 

 attached to Chcvtoinorpha inelagoniain. m August. They bore plenty of tetras pores. 



Locality: Kuovvii ouly from the Greenland Sea at Fairhaveu oii the uorth-west 

 coast of Spitzbergen. 



Fam. PORPHYFtACE^ (Kutz.) Thub. 



in Le Jol. Liste Alg. Cherb. p. 16; Kutz. Phyc. gener. p. 382; char. mut. 



Gen. Diploderma nob. 



Thallus niembraniiceus duobus ctUularum stratis coustiuctus. 



Diploderma amplissimum nob. 



Planta initio aliis algis arinata, demum solula in raari libera circumnatans, fronde usque 90 cm. longa, 

 .30 cm. lata, ovata, ovato-cordala, oblongo-obovata, oblongo-lanceolata, crebre et profiinde uudulato-plicata, non 

 lobata, juvcnili intense violaceo-puipurea, ielate provectiore plus minus dilute violaceo-carnea, lubrica, chartee 

 arctissime adliaerente; cellujis mcdii llialli plantic adultie sectione transversali quadratis vel verticaliter rectaugu- 

 laribus; organis reproductionis zoiiam margiiialem subHavam occupaiitibus. Tab. 17,. lig. 1 — 3; tab. 18, fig. 1 — 8. 

 Syn. Porphyra laciniata f. linearis et vulgaris Kleen, Noidl. Alg. p. 23. 

 » coccinea Kleen, Nordl. Alg. p. 24. 



Ulva umbilicalis /i purpurea Wg. Fl. Lapp. p. 506. 



Deseription of the species. This alga is at first attached to other algte by raeans 

 of a feeble holdfast. At this time it lias a strong, satiirated, purplisli-violet colour. After 

 having attained a more considerable size, it is loosened and lloats about on the surface of 

 the water. In proportion as it grows hirger and older, it bleaches more and more, passing 

 finally to a livid fiesh-colour inclining to violet. The largest s|jecimen I have found 

 attached vvas 28 cm. long by 12 cm. broad at its broadest place. Drifting individuals 

 reach a considerable size. I have nicasured one that was 90 cm. in length by 30 cm. 

 in breadth. The shape of the frond is subject to great variation, but in general it is 

 obloiig, inclining to cordiform or ovate. It sometimes bends round the fastening-point 

 by developing one side more strongly, so as to get, when this bent is at its strongest, 

 an appearance resembling that of Porphyra laciniata f. umbicalis. It is densely folded, 

 often so deeply that the folds extend to the middle line of the frond. The margin is 

 either even or irregularly laciniate, sometimes, though rarely, beautifully crenulated. I 

 have not seen aiiy lobed specimens; tab. 17 fig. 1 — 3. The stipital portion of the 

 frond is coniposed of claviform cells with the shafts directed downward and more or 

 less obliquely outward, shooting beyond one another (tab. 18, fig. 1, 2). In fully de- 

 veloped individuals the cells at the middle of the frond, in cross section, are generally 

 squarish, sometimes rectaugular, considerably more high than long. I cannot determiue 

 at present wliether this difference denotes different ages or different forms. The shape 

 and disposition of the cells as seen from the surface, is shown in fio;. 3. It should be 

 remarked, however, that tiiis figure as well as the others are drawn from dried and 



