( 164 ) 



regularly pinnated plumules ; the pinnte rather erect, and somewhat 

 inciu'ved, thickened upwards, and tapering to the base, with very short, 

 acute apices. Articulations of the stem and branches two to three times 

 as long as broad, those of the ramuli once or once and a-half, each 

 generally producing a branchlet at its apex. Substance rather firm and 

 subcartilaginous, scarcely adhering to the paper, even in its younger 

 part. Colour, a deep dark brownish purple. Favellie bilobed, roundish 

 oval, terminal on abbreviated plumules. Tetraspores roundish oval, 

 sessile on the upper edge, and mostly near the apices of the plumules. 



A very fine species, and not difiacult to understand, being easily 

 known by its long slender branches and short closely plumose ramuli, 

 thickened almost to the penultimate joint, and then suddenly acuminated 

 or rather acute. 



We have not met with it on the east coast; the species, however, 

 seems to be pretty generally distributed, and appears to be not uncom- 

 mon on the south-west of England as well as on most of the Irish coasts, 

 and on the Continent extends from the shores of the Baltic to those 

 of the Mediterranean. — Phyc. Brit. 



It seems very partial to the fronds of Laminaria digitata, but grows 

 also on those of Polyides rotundus, Chondrus crisjuis, and perhaps many 

 others. Of the large fronds of the first it often fringes the margin 

 from end to end, and the paler greenish brown of the frond is finely 

 contrasted with the deep reddish brown of the rich and delicate border. 



EXPLANATION OF PLATE CXXL 



Fig. 1. — GcdlitJiamiiion tetragonum, natural size. 

 2. — Pinna with tetraspores. 

 3. — Tetraspore from same. 

 4. — Pinnre with favellse. 

 5. — Portion of stem. All magnified. 



