H 



! 



I 



1 



W. WEST AND G. S. WEST: ALGA-FLORA OF YORKSHIRE. 29 



Genus LEPTOSIRA Borzl, 1883. 



98. Leptosira mediciana Borzi. 



]S[.E. — Pilmoor, near Thirsk, among Utricularia mmor. Small 

 forms, thickness of cells 7 ■5— 11-5 /x. . 



A characteristic and very rare plant, only previously recorded 

 from Italy. This reminds one of a young stage of Microthamnion 

 kiitzingianum, but is less elongate, the cells are somewhat 

 swollen and barreUshaped, the cell walls are stronger and the 

 celhcontents are of a well-marked yellow-green colour. 



Genus MICROTHAMNION (Nag., 1849) Kirchn., 1S78. 



99. Microthamnion strictissimum Rabenh., 



1863. 



[Syn. M. vexator Cooke, 1882]. 



Bing- 



S.W.—Greetland, near Halifax. Oxenhope. Allerton. 

 ley. Keighley Moor. 



Mid W.— Above Eldwlck. Blubberhouses ! (W. B. Turner). 

 Bogj two miles south of Clapham. 



N.W.— Mickle and Great Shunnor Fells. Masham. 



N.E.— Seamer. Scarborough Mere. 



We have already shown that M. vexator Cooke must be re- 

 garded as identical with M. strictissimum Rabenh. (cfr. Journ. 

 Roy. Micr. Soc, 1897, p. 475). Schmidle (in Hedwigia, 1899, 

 Bd. xxxviii., p. 169) has placed M. vexator as a variety of M, 

 strictissimum, hwi we fail to see any distinction between the plants. 



100. Microthamnion kiitzingianum Nag. 



Not common, but more abundant than the preceding species, 

 and most abundant in the earlier months of the year. A more 

 diminutive plant than the preceding species and much more 



branched. 



S.W.— Cragg Vale, towards Blackstone Edge. Bradford. 



Frizinghall. Marley, near Binglcy. 



Mid W.— Above Eldwick. Boston Spa. Cocket Moss near 



Giggleswick. Horton-in-Ribblesdale. Oughtershaw Tarn. Cam 



Fell. Whernside. Cowgill Wold Moss, Widdule Fell. 



ii 



