22 YORKSHIRE NATURALISTS UNION. 



Only known elsewhere in the British Isles from Glen Tilt, 



Perthshire. 



Sub-Family CH/ETOPHOREiE. 



Genus HERPOSTEIRON Nag., 1849. 



66. Herposteiron repens (A. Br.) Wittr. [Syn. Aphano- 



chcBte repens A. Br., 1851, non Berth., 1878]. 



S.W. — Frizinghall, on CEdogonium sp. and Cladophora flaves- 

 cens. Bradford, in aquarium, on Lemna trisuka and Elodea 

 canadensis. 



Mid W. — Hawksworth, on Cladophora. 



N.E. — Pilmoor, near Thirsk. Terrington. 



Herposteiron Nag. is distinguished from Aphanochate Berth, 

 by the structure of its bristles ; they are articular and strongly 

 remind one of the piliferous apices of the branches of Chato- 

 phora. Those of Aphanochaie are quite simple and possess a 

 sheathing base, which is not septate. In both these genera the 

 chlorophyll masses are parietal. These plants are usually found 

 as epiphytes on larger algse (Cladophora, CEdogonium, etc.) and 

 on Lemna, Elodea, Nitella, etc. 



Genus NORDSTEDTIA Borzi, 1892. 



67. Nordstedtia globosa (Nordst.) Borzi. [Syn. Herpo- 



steiron globosa Nordst. ; Aphanochceie globosa WoUe]. 



Mid W. — Cocket Moss, near Giggleswick. 



N.E. — Strensall Common. 



S.E. — Skipwith Common. 



The cells of this plant are spherical and each bears on its 

 dorsal surface a very long seta, which is quite simple. The 

 chromatophores are central and more or less stellate, and the 

 plants are enveloped in mucus. 



Genus CH^TO-SPHERIDIUM Klebahn, 1892. 



68. Chsetospheridium minus Hansg., 1893, [Syn. 



Aphanochceie globosa var. minor Hansg. ; Chceto- 

 spheridium Pringsheimii Klebahn, 1892]. 

 N.E. — Pilmoor, near Thirsk. 



Trans. Y.N.U., 1896 (pub. Sept. 1900). Bot. Series, Vol. 5. 



