92 YORKSHIRE Naturalists' union'. 



with a short and open sinus ; semicells subtrapeziform, with the 

 superior angles obliquely truncate, with the sides diverging up- 

 wards, apices broad, straight or very slightly retuse ; from the 

 side view subcircular ; vertical view elliptic-oblong, with some- 

 what acute poles, slightly tumid on each side in the middle, 

 on each side towards the poles furnished with a small papilla : 

 pyrenoids single. Length, io"5-ii'5/^; breadth, ii-i3'5/^; 

 breadth of isthmus, 5-5"5 /a; thickness, 6"5 /x. 



Mid W. — Cocket Moss, near Giggleswick. 



N.W.— Mickle Fell. Mossdale Moor, Widdale Fell. 



This minute species occurs occasionally in immense quantity 

 amongst Sphagnum in small, peaty pools. It is most nearly 

 related to C. Heimerlii var. tumidum in vertical view, but the 

 front view is quite distinct ; it may also be compared with C. 

 Regnesii var. montantim Schmidle. 



417. Cosmarium truncatellum (Perty) Rabenh. 

 N.E.— Strensall (W. B. Turner). 



418. Cosmarium abruptum Lund. 

 N.W. — -Mickle Fell, very scarce. 



419. Cosmarium abbreviatum Racib. 



N.E. — Pilmoor, near Thirsk. 

 S.E. — Skipwith Common. 



Forma minor. 

 S.E. — Skipwith Common. Only half the size of the type; 

 length, 8 />i; breadth, 9 \i.. 



420. Cosmarium pygmaeum Arch. 

 N.W.— Mickle Fell. 



421. Cosmarium impressulum Elfv. [Syn. C. crenu- 

 latum (Ehrenb.) Breb. var. Reinschii Schmidle 1893; 

 C. Me/ieghitiii V>x&o. f. Reinschii Istw. 1887]. 



Mid W. — Malham Tarn. 

 N.E. — Pilmoor, near Thirsk. 

 S.E. — Hornsea Mere. 



422. Cosmarium umbilicatum Liitkem. 

 N.E. — Malton (viii. 1899). 



Trails. Y.N.U., 1S97 (pub. Dec. 1900). Bot. Series, Vol. 5. 



