220 KJELLMAN, THE ALG^ OF THE ARCTIC SEA. 



However, the proper season for produciiig zoospores appears to be låter, probably in 

 the rnonth of June. 



Geogr. Distrib. At present this species is known with certainty in the Arctic 

 Sea only from the easteni part of the Siberian Sea. Here it was everywhere found 

 abundant. 



Localities: The Siberian Sea: Koljushin Isle, and at two places eastward of the 

 mouth of Koljushin Bay, abundant. 



The American Arctic Sea: the north coast of Western Eskimaux-land (?). 



Alaria obion ga nob. 



A. stipite perbrevi, vix ultra pollieari, tcrete; rhachide demiim pluripollicari, apicein versus incrassata, 

 compressa, in sectione traiisversali elliptica, lesicluis spoioph_vllorum alijectorum in plantis senilibus longe deorsum 

 plus minus distincte rauiiculata, abiuptc in costam abeunte; lamina elongata, lineaii-oblonga, basi ovata, vix 

 decurrente vel ovato-coidata, usque 25 cm. lata, tenue raerabranaeea, undulata; costa prominula, in sectione 

 transversali elliptica; sporophyllis numerosis, subdistantibus, petiolatis, lanceolato-spatliulatis, augustis 1,5 — 2 cm. 

 latis, steriiibus tenue niembnuiaceis, parte fertili subpergamcis, margiuo uudulato-crispatis, longe infra apicem 

 sorura formautibus. Tab. 22 et 25 fig. 21 — 24. 



Description. The rhizines issue in alternate whorls and are subdichotomously 

 branched. The branches in the present species as in other LaminariaceEe are shorter 

 and more robust as the substratum is niore solid. 



The stipe is very short, sometirues almost imperceptible, on account of the cauloid 

 portion bearing or, as is shown by the cicatrices, having borne sporophylls immediately 

 above the rhizines. Its length in older individuals usually varies between 0,5 and 2 

 cm. In very young individuals the stipal part may be distinguished from the rhachis 

 by the latter being thicker. In very old specimens the limit between these two parts 

 of the cauloid portion is indistinct on account of the cicatrices of the fallen first sporo- 

 phylls being effaced. In outline the stipe is terete downwards, somewhat, but only slightly, 

 compressed upwards, where it passes into the rhachis. In the oldest individuals I met 

 with, the stipe was 5 mm. in diameter. 



The rhachis increases in length as the plant grows older, attaining a length of at 

 least 14 cm. It is almost terete downwards, but upwards it is flatteiied and thicker. 

 Above the uppermost sporophylls it tapers swiftly, soon passing into the costa. The 

 part with sporophylls is flatly elliptical in protile, at least 8 mm. in its longest dia- 

 meter. The difference in shape and thickness between the stipe and the rhachis in the 

 same individual is shown by fig. 21 and 22 in tab. 25. 



The lamina, as shown by the figures of tab. 22, in younger as well as older 

 specimens has almost perfectly the same shape, elongatedly linear-oblong, or in other 

 words linear-lanceolate, with rounded base which is not at all or almost imperceptibly 

 decurrent. It sometimes tapers towards its extremity somewhat more swiftly and 

 strongly than in the specimens delineated, and sometimes in very old specimens the 

 base is almost cordate. The lamina attains a considerable size, but it is only seldom 

 that a specimen is found with the whole lamina preserved. In my collections I have 



