KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 20. N:o 5. 219 
shows the central fibrous layer to be lanceolate or sickle-shaped in A. esculenta, but 
more plainly linear in A. dolichorhachis. The surrounding cell-layer, a tissue most nearly 
related to the collenchyme and constituting together with the central layer the mechanical 
system, possesses longer and wider elements in A. dolichorhachis 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. dolichorhachis than in A. esculenta and has a strong tendency 
to burst radially in drying. The outside of the cauloid portion of A. dolichorhachis 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 u. or even more. 
Here and there in it cavities are formed extending lengthwise as well as radially and 
finally opening outwards. These sometimes much resemble the lacunw muciferw 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. Pyludi, A. membranacea, 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. 
AGarpDH was distributed by Ruprecut under the name of Phasyanon alatum. Cp. J. G. 
Ac. 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 alge collected by Srrman. 
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 Laminariacew, Laminaria cuneifolia and L. 
solidungula, «a well-marked formation of Laminuriacew. 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. 
