(90) 



end, patent ; the axils wide but not rounded, all the apices very 

 much acuminated, and frequently forked, the forks long and slender. 

 Structure cellular ; cells large, quadrate, forming a thin hollow cylinder. 

 Substance delicately membranous, and closely adhering to the paper. 

 Colour, a rather pale yellowish olive. Fructification : roundish spores, 

 collected into roundish dot-like sori, which form transverse rings round 

 the whole of the frond at a distance of a quarter of a line apart ; 

 the spores are of a dark olive coloiu-, and enveloped in a thin pellucid 

 limbus. 



We are informed in Phyc. Brit, that the present plant was first 

 noticed as British by the late Captain Carmichael, of Appin, a most 

 indefatigable and accurate observer among the marine Algse of his coast, 

 and one to whom the British botanist is indebted for much information 

 respecting the Algse of the west coast of Scotland. Since his discovery 

 of the present species in 1826, it has been observed both in England and 

 Ireland, but is by no means common. The only specimens we have seen 

 are from Plymouth, a locality extremely favourable to the growth of 

 Algse. 



From the species of the two preceding genera it may be readily known 

 by the much wider tube, its thin walls, the very much attenuated bases 

 of the branches, the grouping of the naked spores, and the difierent 

 arrangement of the groups. 



Its favourite habitat is said to be in quiet sheltered bays with a 

 rather soft bottom, preferring, however, to grow parasitical on other 

 Algee to the trouble of laying a foundation for itself on the rocks. 



EXPLANATION OP PLATE CLXIL 



Fig. 1 . — Striaria attenuata, natural size. 

 2. — Branch with part of its ramulus. 

 3. — Surface cells and sorus. 

 4. — Spores. All magnified. 



