148 YORKSHIRE NATURALISTS' UNION. 



734. Phormidium autumnale (Ag. 1812) Gomont, 

 1893. [Sy"- Oscillatoria autumnalis Ag., 1812; 

 O. antilaria Martens, 1822 ; Phormidium vulgare 

 Kiitz., 1843; Lyngbya vulgare (Kiitz.) Kirchn. 



; Oscillaria subfiisca Kiitz., 1843]. 

 S.W.— Horton Park, Bradford. Clayton. Shipley. 

 Mid VV. — Baildon. Markington ! (Rev. J. S. Tute). 

 N.E. — Strensall. Scarborough ! (G. Massee). 



735. Phormidium foveolarum (Montague, 1849) 

 Gomont, 1893. 



Mid W. — Boston Spa, forming a dark green stratum in holes 

 of limestone rocks. 



Genus CLONOTHRIX E. Roze, 1896. 



736. Clonothrix graciilima West & G. S. West 

 Trichomes very narrow, alternately falsely branched ; false 



branches flexuose and sometimes attenuate, elongate with 

 alternate false branchlets; sheaths thin, firm, straight and 

 colourless ; cells three to four times longer than the diameter, 

 cytioplasm bright seruginose. Trichomes i"S /i in thickness. 



S.W.— Trough, Shipley. 



N.E. — Pilmoor, near Thirsk. 



The false ramification of this plant is most peculiar; the 

 apparent branches seem to be merely tangentially applied at 

 their bases to the primary filaments, and are of the same 

 thickness. The ' branches ' appear to arise by the lateral protension 

 of a few cells from the sheath ; these cells remain attached 

 laterally and grow quite independently into long flexible filaments. 

 The cells were often seen to have left the sheath, the latter 

 being empty for some distance. 



The only other species of the genus is C. fitsca E. Roze 

 (Journ. de Botanique, Oct. 1896, p. 329-330), from which it is 

 distinguished by its much narrower trichomes of uniform 

 thickness, its more elongate false-ramifications, and by its 

 bright blue-green colour. 



Trans. Y.N.U., 1899 (pub. July 1901). Bot. Series, Vol. 5. 



