KONGL. SV. Virr. AKADEMIENS IFANDLINGAU. HANI) 26. N:0 2. 1 (Jl) 



Lunula A. S. Atl. X f. 42, 43; LXXI f 14, 15, 32 to 34. Cijmh. Lunula Rabii. A]g. Eur. N:o 

 mm (IS(il). Gi/mb. siksiuca Blkiscii Rabh. Alg. Eur. N:o 1802 (ISBf)). A. S. Atl. X f. 5!). Cymh. 

 minuta Hilse Rabii. Alg. Eur. N:o 1201 (18(;2). A. S. Atl. LXXI f. 30, 31. Cymh. variahilis 

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



Fre.sli water: Spitsbergen! Norway (Dovre, ('liristiania)! Sweden (Lapland to Skane)! Fin- 

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

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

 Ecuador ! 



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

 middle of the valve. — Encyon. crcspit. var. ovata A. S. Atl. X f. 45, 46. V. H. Syn. PI. Ill f. 13. 



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



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

 Atl. X f. 47, 48. 



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



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

 nenia ventricosum and E. cfespitosnin, the former being smaller and with the median line closer to 

 the sti'aight 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) Jordan! Grun. Ms. — V. with very elevated dorsal mai-gln, more or 

 less gibbous ventral margin and truncate to capitate ends. L. 0,o2 to 0,o32; B. 0,oo8 to 0,oo9 mm. 

 Areas indistinct. Median line straight; its terminal fissures turned downwards. StriiB about 1<) 

 in 0,0 1 mm., radiate in the middle, very finely punctate. — PI. V f. 3, 4. 



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



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

 and slightly convex ventral margin and subacute ends. L. 0,o.'5 to 0,o4; B. 0,oo7 to 0,oo8 mm. 

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

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

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

 Cl. D. of Finl. p. 48 PI. II f. IG, 17. 



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

 Viborg foss.)! 



This form, Avhich appears to be pretty constant, occxirs in northern regions. It connects 

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

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



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

 dorsal and straight ventral margin. Ends acute. L. 0,o3 to 0,056; 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. StrijE 10 to 13 in 0,oi mm. — Encyon. yracile Rabii. Siissw. I). PI. X 

 f. 1. A. S. Atl. X f. 3G, 37, 39, 40. V. H. Syn. PL III f. 20 to 21. Cymhella scotica VV. Sm. 

 B. D. I p. 18 PI. II f. 25 (1853). C^jmh. lunuta W. Sm. Ann. Mag. Nat. Hist. [2] XV PL IX f. 15 

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



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

 land)! Finland! Scotland! Savoy! Ta.smania! New Zealand! Gi'eenland! "White Mountains! 



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

 broad ends. L. 0,o4 to 0,o5; B. 0,oo7 to 0,008 mm. Median line straight, nearly axial, with the 



K. .Sv. Vet. Akadciiiicns lliimlliiis'-iir. HJ 2(j. N:o 2. S'i 



