KONGL. 8V. VET. AKADEMIENS HANDLINGAE. BAND 26. N:0 2. 169 



Lunula A. S. Atl. X f. 42, 43; LXXI f. 14, 15, 32 to 34. Cymb. Lunula Eabh. Alg. Eur. N:o 

 1166 (1861). Gymi. silesiaca Bleisch Rabh. Alg. Eur. N:o 1802 (1865). A. S. Atl. X f. 59. Cymi. 

 minuta Hilsb Rabh. Alg. Eur. N:o 1261 (1862). A. S. Atl. LXXI f. 30, 31. Cymb. variabilis 

 Wartm. Rabh. Alg. Eur. N:o 803 (1859). 



Eresh water: Spitsbergen! Norway (Dovre, Christiania)! Sweden (Lapland to Skane)! Fin- 

 land! Gulf of Bothnia (from Haparanda to Roslagen)! England! Belgium! France! Germany! Swit- 

 zerland! East Indies! Japan! Australia! Tasmania! New Zealand! Greenland! Mexico! California! 

 Ecuador! 



Var. ovate Grun. (1875). — V. with convex ventral margin. Median line almost in the 

 middle of the valve. — Encyon. cmspit. var. ovata A. S. Atl. X f. 45, 46. V. H. Syn. PL III f. 13. 



Fresh water: Sweden (Gulf of Bothnia)! Germany, Atter See (Atl.), Belgium (V. H.). 



Var. obtusa Grun. (1875). — V. elongated, obtuse. — E. cesspit, var. obtusa Grun. in A. S. 

 Atl. X f. 47, 48. 



Fresh water: Rome (Atl.), Rammer Moor (Atl.). 



Most authors regard the forms of C. ventricosa as belonging to two different species, Encyo- 

 nema ventricosum and E. ccespitosum, the former being smaller and with the median line closer to 

 the straight ventral margin, the latter a little larger, with the median line somewhat more distant 

 from the ventral margin, which is slightly gibbous in the middle. I am unable to find any definite 

 limit between these species, and as their distinctive characteristics are very trifling and subject 

 to great variation, I have united them. 



40. C. (Encyonema) Jordani Grun. Ms. — V. with very elevated dorsal margin, more or 

 less gibbous ventral margin and truncate to capitate ends. L. 0,02 to 0,o32; B. 0,oo8 to 0,oo9 mm. 

 Areas indistinct. Median line straight; its terminal fissures turned downwards. Striae about 16 

 in 0,01 mm., radiate in the middle, very finely punctate. — PL V f. 3, 4. 



Fresh water: Otago, New Zealand (Weissflog Coll.)! 



41. C. (Encyonema) hebridica Grun. (1877). — V. elongated, lunate, with arcuate dorsal 

 and slightly convex ventral margin and subacute ends. L. 0,03 to 0,04; B. 0,oo7 to 0,oo8 mm. 

 Median line straight, dividing the valve so that tbe ventral part is half as broad as the dorsal. 

 Terminal fissures in the ends. Axial area very narrow; central area small or indistinct. Strise 

 about 10 in 0,oi mm. distinctly punctate. — Encyon. hebridicum (Greg.) Grun. CI. M. D. N:o 37. 

 Cl. D. of Finl. p. 48 PL II f. 16, 17. 



Fresh water: Sweden (Lulea Lapmark, foss.)! Finland (Russian Lapland; Nyland and 

 Viborg foss.)! 



This forjn, which appears to be pretty constant, occurs in northern regions. It connects 

 E. ventricosum with E. gracile. In A. Schmidts Atl. IX f. 11 is figured a large form from »Ohla- 

 jarris (Orrjarvi, Finland?), which seems either to be a forma maxima of C. hebridica or a new species. 



42. C. (Encyonema) gracilis Rabh. (1853). — V. narrow, slender, with gently arcuate 

 dorsal and straight ventral margin. Ends acute. L. 0,03 to 0,o56; B. 0,oo7 to 0,oi mm. Median 

 line more approximate to the ventral than to the dorsal margin; its terminal nodules distant from 

 the ends. Areas indistinct. Striae 10 to 13 in 0,oi mm. — Encyon. gracile Rabh. Siissw. D. PL X 

 f. 1. A. S. Atl. X f. 36, 37, 39, 40. V. H. Syn. PL III f. 20 to 21. Gymbella scotica W. Sm. 

 B. D. I p. 18 PL II f. 25 (1853). Cymb. lunata W. Sm. Ann. Mag. Nat. Hist. [2] XV PL IX f. 15 

 (1855). V. H. Syn. PL ni f. 23. 



Fresh water, especially alpine regions: Norway (Finmark, Dovre)! Sweden (Lapland, Sma. 

 land)! Finland! Scotland! Savoy! Tasmania! New Zealand! Greenland! White Mountains! 



43. C. (Encyonema) norvegica Grun. (1875). — V. asymmetrical, linear, with obtuse, 

 broad ends. L. 0,o4 to 0,o5; B. 0,oo7 to 0,oo8 mm. Median line straight, nearly axial, with the 



K. Sv. Vet. Akademiena Handlingar. Bd 26. N:o 2. 22 



