Fig. 171. DELESSERIA ALATA. 



Colour. A deep red. 



Substance. Side-wings membranaceous; midribs elastic and firm. 



Character of Frond. Stems and branches winged with a deUcate membrane on each 

 sid^; nowhere furnished with distinct leaves. But in luxuriant specimens, the 

 winged membrane has side-veins, similar to those of a leaf. Stem compressed; 

 several times forked (dicJiotomozts) ; or excessively but irregularly branched. 

 Margins whole {entire^. Tips often cleft, and overlapping. 



Measurement. Frond from 3 to 8 inches high. Branches from -^^ to ^ of an inch 

 wide. 



Fructification. Of two kinds, 1. A mass of spores in globose capsules, imbedded 

 in (but prominent above) the midribs; towards the extremity of the branchlets. 

 2. Tetraspores imbedded either in minute leaflets springing from the midrib 

 either at or near the tips, or in the tips themselves. Leaflets springing from 

 the midribs. 



Habitat. Our coasts generally. On rocks; the stems of Laminaria digitata, and 

 other large algse, and in from four to ten fathoms water. Common. 



So different in the width of the winged membrane that the young student 

 may easily be led to suppose that he has got hold of a different species in the 

 different varieties. Sometimes from the abundance of leaflets growing out of 

 the midribs the whole upper part of the frond is thick and bushy. Refer back 

 to Plate XXXIII. Fig. 150, for Delesseria angusfissima, which is suspected to be 

 only a narrow variety of D. alata. 



Fig. 172. DELESSERIA HYPOGLOSSUM. 



Colour. A fine pinky red, soon given out in fresh-water. 

 Substance. Delicately membranaceous. 



Character of Frond. Composed entirely of leaves growing from leaves; the younger 

 from the midribs of the older, in several series; so that the tout ensemble in 

 full-grown specimens is globose. Leaves linear-lanceolate, tapering at each 

 end; margins whole {entire^. Midribs distinct; side-veins faintly marked; 

 transparent. Branchlets springing from the midribs. 



Measurement. Most variable. Leaves sometimes of an inch wide; sometimes \ 

 an inch. Fronds from an inch to J a foot high. 



Fructification. Of two kinds. 1. A mass of spores in globose capsules, immersed in 

 (but prominent above) the midribs of the leaflets. 2. Tetraspores forming 

 linear groups on each side of the midrib. 



Habitat. Our shores generally. On rocks and algie. Not uncommon, though rare 

 in Scotland. 



At Cushendall, Co. Antrim, the frond grov/s from three to four feet long. 

 But this is a very unusual size. Even in the nurrowest varieties, however, 

 the character of the species is preserved; i. e. the growth of the leaves from 

 the midribs of others; a peculiarity the figure does not make sufficiently clear, 

 as the leaflets there have the appearance of springing from the margins of the 

 preceding set, which is not the case. B. liypoglossum cannot be confounded 

 with any other plant, with the exception of Delesseria ruscifulia; but D. hyiw- 

 glossum is of a brighter colour; thinner; and its leaves are longer and narrower 

 in proportion, and pointed instead of obtuse at the tips. For another Delesseria 

 see Plate XL. Fig. 182, where the characteristic growth of that species and the 

 present is better given. 



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