BYNOPSIfl OF BRITI-H 9EAWBXD8. 



1(17. Hypoglossum {The proliferous Delesserid) \ frond li- 

 near-lanceolate, tapering at each end, repeatedly proliferous 

 from the midrib, with leaflet* of similar form ; tubercl 

 the midribs of the smaller leaflets ; granules forming Linear 

 spots ai each side of the midrib, Ag. Sp, Alg. v. l.o. J7»>. 

 lb, I'!. WWII. Pig. 172.) 

 Wormskioldia Hypoglossum, Spreng. Hypoglossum "Woodwar- 

 dii, Ktz. Fucus Hypoglossum, Woodw. P. hypoglossoides, 

 stark. Ulva lingulata, De Cand. 

 llah. Atlantic shores of Britain. In the sea, on rocks and Algce. 

 Annual. Summer. Frequent. 

 This species varies indeed greatly in size, the frond being 

 sometimes scarcely a line in width, sometimes nearly half 

 an inch ; but its admirable distinguishing character, that 

 of being repeated]) proliferous from the midrib, is invari- 

 able. The only British plant with which a young botanist 

 can confound it, is the somewhat rarer D. ruscifolia, from 

 which its thinner substance, brighter colour, proportionally 

 narrower leaves, and the lanceolate, not linear-oblong, form 

 of the leaflets, distinguish it. 



1G8. ruscifolia (The obtuse-leaved Delesseria) ; frond linear- 

 oblong, obtuse, repeatedly proliferous from the midrib with 

 leaflets of a similar form ; leaflets traversed by oblique, 

 anastomosing, pellucid striae ; tubercles on the midribs of 

 the smaller leaflets ; tetraspores forming linear spots at each 

 side of the midrib, Lamour. Ess. p. 124. (Atlas, PL XL. 

 Fig. 182.) 

 Wormskioldia ruscifolia, Spreng. Hypoglossum ruscifolium, Ktz. 



Fucus ruscifolius, Turn. 

 Ilab. G-enerally growing on rocks, near low- water mark; some- 

 times parasitical on other Alga?. Annual. Spring, summer, 

 and autumn. 

 The differences between this and the preceding species 

 are as follows. In D. Hypoglossum the leaflets are lanceo- 

 late, tapering to each end, and generally, but not con- 

 stantly, acute ; in D. ruscifolia they are linear-oblong, 

 much broader in proportion to their length, and always 

 very blunt. But besides differences of form, which are not 

 always constant, the cellules composing the membrane in 

 the present species are much smaller, the substance denser 

 and thicker, and the colour more intense than in D. Hypo- 

 m ; while the confervoid striae which traverse the 

 . and are readily seen in I). ruscifolia, are either 

 very obscure or do not exist in I). Hypoglossum. 



