MARINE ALGJil. 5 



nigrescens, and L. littoralis ; and even in L. ovata the " Trichtcr " (as Grabendorfer 

 calls them) differ in being more inflated at their funnel-shaped ends and quite 

 destitute of a special sheath. 



In the very young lamina (^ in. long), the structure is much simplified (fig. 6). 

 The cortical cells are crowded, and obscured by coloured granules and form a mono- 

 stromatic layer, beneath which is the subcortical stratum of about 2 rows of large cells, 

 round in transverse section, or sometimes twice as long as broad in longitudinal section 

 of lamina (fig. 8). In the middle lies the medulla, consisting of some three or more 

 rows of longitudinal or transverse hyaline hyphse ; among them are very few trumpet- 

 hyphse, each in its sheath. 



As to the structure of the stipes, it is in the main similar to that of the mature 

 lamina, but the cortex is a little thicker and more deeply coloured, the medulla is 

 far thicker and the sub-cortical layer much less distinct. In a transverse section 

 there is a narrow, more opaque, median band stretching right across, along the widest 

 diameter, distinctly visible to the naked eye (fig. 3b). This, under a low power of the 

 microscope, is seen to contain dots and streaks (fig. 3c, and 4), which, under a higher 

 power, are seen to be trumpet-hyphse in transverse and longitudinal section (fig. 9). 



The structure of the basal holdfasts is simple, the main tissue being composed of 

 thin hyaline hyphse mainly longitudinal, most of them exhibiting a contracted globose 

 mass of coloured protoplasm ; this tissue contains no ensheathed trumpet-hyphse and 

 passes gradually through a cell-like subcortex to a submonostromatic cortex of small 

 cells obscured by coloured granules. 



Neither stem nor lamina possess any lacunae like those that characterise L. 

 nigrescens and other species. 



L. grandifolia resembles our L. simulans in external habit, but differs in structure, 

 as we show under that species. It also approaches L. laminarioides in habit, but 

 differs from it in being 10-20 times as large, in having the stems flat and twisted, and 

 the medullary hyphse interspersed with the ensheathed trumpet-hyphse mentioned 

 above. L. ovata, though, as we have said, possessing trumpet-hyphse somewhat like 

 those of our plant, is otherwise very different, having small oval laminae less than 

 20 cm. long, and a stem which, according to Grabendorfer {op. cit., p. 643), may attain 

 a length of several metres and a thickness of about 10 cm. 



3. Lessonia simulans. 



(Plate II., fig. 16.) 



L. simulans Gepp, Journal of Botany, 1906, p. 425. 



L. grandifolia, pro parte Gepp, op. cit, 1905, p. 105, tab. 470, fig. 6. 



Planta incompleta. Frons laminarioidea ut in L. grandifolia, stipite complanato 

 ancipite suffulta simplex, lanceolato-linearis, longa, lata (12-5 cm. plusve) marginibus 

 integerrimis. Laminae substantia pergamentacea vel coriacea e stratis tribus com- 

 posita ; cellulis corticalibus monostromaticis quadratis granuloso-obscuris ; subcorti- 



