J20 YORKSHIRE NATURALISTS UNION. 



ADDENDA. 



tlEXUS COSMARIUM Corda, 1834. 



1043. Cosmarium subreniforme Nordst. in Ofvers. 

 af K. Vet. Akad. Forh. 1875, no. 6, p. 24, t. vii., 

 f. 16. 



N.E. — Strensall Common. 



This species has not previously been recorded for the British 

 Isles. 



He.nus TETRAGOXIUM West & G. S. West, 1896. 



1044. Tetragonium lacustre West & G. S. West, in 

 Journ. Roy. Micr. Soc, 1896, p. 160, t. ii., f. i — 13. 



S.AV. — Shelf: abundant in pools. 



This plant is known elsewhere from Surrey and Lancashire. 



