KONGL. SV. VET. AKADEMIENS HANDLINGAK. BAND. 20. N:0 5. 219 



shows the central fibrous layer to be lanceolate or sickle-shaped in A. esculenta, but 

 more plainly linear in A. doUchorhachis. The surrounding cell-layer, a tissue most nearly 

 related to the coUenchyme and constituting together with the central layer the mechanical 

 system, possesses longer and wider elements in A. doUchorhachis than in A. esculenta. 

 The tissue covering this layer shows a greater or less number of concentric zones in the 

 former species, but not in the latter, as far as my observations go. Besides, it is of a 

 looser consistency in A. doUchorhachis than in A. esculenta and has a strong tendency 

 to burst radially in drying. The outside of the cauloid portion of A. doUchorhachis is 

 composed of a tissue whose cells are transversely rectangular or square, arranged in 

 pretty regular radiating rows and furnished with thin brown walls. This tissue, 

 which I have never found in A. esculenta, is assuredly most closely allied with cork 

 tissue. In older individuals it attains a considerable thickness, 150 ,m. or even more. 

 Here and there in it cavities are formed extending lengthwise as well as radially and 

 finally opening outwards. Thpse sometimes much resemble the lacunae muciferse that 

 occur in certain species of the genus Laminaria. On this account the surface of the 

 cauloid portion upwards to the rhachis is usually fissured and uneven in older specimens. 



I have collected a considerable number of the Alaria now described of different 

 ages at different rather widely distant points on the north coast of the Tshutsh-land. 

 It is undoubtedly specifically distinct from the species of Alaria occurring in the At- 

 lantic Sea and in the Arctic Sea north of the Atlantic. It might be taken at first sight 

 for an A. esculenta f. typica, because it resembles this species most with regard to the 

 form of the lamina. It is however decidedly distinguished from it by several strongly 

 marked characteristics, as the form of the rachis and the costa a. o. In the shape of 

 the rhachis it agrees most nearly with the group A. Pylaii, A. inemhranacea, and A. 

 grandifolia, but it is known from all of these by the shape of the lamina as well as of 

 the costa. That it differs in the shape of the costa both from these species and from 

 A. esculenta, is shown by a comparison between fig. 16, 19, and 20 in tab. 25. 



Older individuals of the present species have a very characteristic aspect on account 

 of the cauloid portion being large and coarse in proportion to the lamina, the rhachis 

 thickening upwards, the sporophylls being very numerous, clustered, often spirally 

 twisted, long and thin. It can hardly be confounded with any species known to me. 

 It exists also in the Behring Sea and is probably that alga which according to J. G. 

 Agardh was distributed by Rupkecht under the name of Phasganon alatum. Cp. J. G. 

 Ag. Gronl. Lam. och Fuc. p. 23. It is possibly the same plant that was brought home 

 by Seeman from the north coast of western Eskimaux-land and has been called A. 

 esculenta by Harvey in his list of the algte collected by Seeman. 



Habitat. It grows within the sublitoral zone in 2 — 3 fathoms water. It prefers rocky 

 bottom, but is found also on pebbly bottom, though less richly developed. It is gre- 

 garious, forming in company with other Laminariacece, Laminaria cuneifolia and L. 

 solidungula, a well-marked formation of Laminariacece. I have seen specimens taken in 

 the Arctic Sea in April, May, and June, all with the lamina preserved and plenty of 

 sporophylls. At the end of April I got some specimens with the sorus developed. 



