KONGL. SV. VET. AKADKMIENS IIANULINGAR. BAND. 20. N:0 5. 231 



Total length of the alga. Length o( the stipe. Length of the lamina. Greatest breadth. 



310 70 240 50 era. 



307 57 



285 35 



241 31 



236 26 



220 25 



216 16 



183 55 



With regard to structure f. grandifolia differs also from the before-mentioned 

 forms by having much wider and more thin-walled elements. This is especially the 

 case with the collenchyme and the adjoining parenchyme of the stipe and with the 

 parenchyme of the lamina. The central layer of the siipe is composed of thinner cells 

 with more swollen membranes. 



The pits of the lamina are sometimes very numerous, sometimes rare. In one 

 specimen I have found a few rugte in the middle part of the lamina. 



In the lamina three parts are distinguishable: the middle part which is smooth 

 or almost smooth, the intermediate part with many depressions, and the marginal part 

 which is thin, wavy, with few depressions. 



L. saccharina f. latissima. This is not the preceding form at a different age, as 

 one might be inclined to suppose. For I have examined young specimens of both the 

 forms that plainly showed the same shape of the lamina as in older individuals. But 

 though I have not seen any transitions between them, they resemble each other in so 

 many respects that they are probably to be considered as less strongly differentiated 

 forms of the same species. Whether this is really L. saccharina or some other species 

 different from it, is a question I must leave undecided at present. Just as f. grandi- 

 folia corresponds to the southern L. saccharina f. membranacea and replaces it in the 

 North, f. latissima may be regarded as a northern form corresponding to a L. saccharina 

 existing at Bohuslan which is distinguished by its short stipe, and thin almost membra- 

 naceous lamina, that is linear with rounded base and wants rugte. From f. grandifolia 

 f. latissima is distinguished almost exclusively by the shape of the lamina. This is in 

 younger individuals almost linear with rounded base, or elongated linear-ovate. When 

 older, it increases considerably in breadth and becomes broadly elliptical with ovato-cordate 

 or cordate base. The surface is sometimes smooth, sometimes covered more or less 

 densely with pits. I have seen one specimen with low rugae. In structure it accords 

 nearly with the preceding form, showing the same differences as this from f. linearis 

 and f. oblonga. The lacunse mucifera? in the lamina are sometimes scarce, sometimes 

 numerous, always large, confined in a greater or less extent of their periphery by cells 

 that are smaller and of another shape than the other cells of the parenchyme. The 

 form in question resembles L. Agardhii even more than f. grandifolia does. It is 

 distinguished from it by the same characteristics as f. grandifolia. It is this form la- 



