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

 Genus LEPTOSIRA Borzi, 1883. 



98. Leptosira mediciana Borzi. 



N.E. — Pilmoor, nearThirsk, among Utricularia minor. Small 

 forms, thickness of cells 7-5 — 11 '5 \i. 



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 barrel-shaped, the cell walls are stronger and the 

 cell-contents are of a well-marked yellow-green colour. 



Genus MICROTHAMNION (Nag., 1849) Kirchn., 1878. 



99. Microthamnion strictissimum Rabenh., 1863. 



[Syn. M. vexator Cooke, 1882]. 



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

 ley. Keighley Moor. 



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

 Bog, 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,hu\. 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 Bingley. 



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

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

 Fell. Whernside. Cowgill.Wold Moss, Widdale Fell. 



