KONGL. SV. VET. AKADEMIENS HANDUNGAR. BAND 26. N:0 2. 169 



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

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

 mimda Hilse Rabh. Alg. Eur. N:o 1261 (1862). A. S. Atl. LXXI f. 30, 31. Cymh. variahilis 

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



Fre.sh väter: Spitsbergen! Xorwaj^ (Dovre, Cliristiania)! Sweden (Lapland to Skåne)! Fin- 

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

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

 Ecuador! 



Var. ovata GtRUN. (1875). — V. witli convex ventral margin. Median line almost in tlie 

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



Fresla water: S-weden (Gulf of Bothnia)! Germany, Ätter See (Atl.), Belgium (V. H.). 



Var. nhtusa Gkun. (1875). — V. elongated, obtuse. — E. ccssjnt. var. ohtusa Grdn. in A. S. 

 Atl. X f. 47, 48. 



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



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

 nema ventricosuvi and E. cmspitosum, 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 anj' definite 

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

 to great variation, I have nnited them. 



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

 less gibbous ventral margin and truncate to capitate ends. L. 0, 02 to 0,032; B. 0,oos to 0, 009 mm. 

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

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



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



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

 and sliglitl}'- convex ventral margin and subacute ends. L. 0,o3 to 0, 04; 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. Strife 

 about 10 in 0,oi mm. distinctly punctate. — Encyon. hehriclicum- (Greg.) Grdn. Cl. M. D. N:o 37. 

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



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

 Viborg foss.)! 



This form, 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- 

 järri» (Orrjärvi, Finland?), which seems either to be a forma maxima of C. hehriäica or a new species. 



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

 dorsal and straight ventral margin. Ends acute. L. 0,o.'j to O.use; 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. Strise 10 to 13 in 0, 01 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. Cymhdla scotica W. Sm. 

 B. D. I p. 18 Pl. II f. 25 (1853). CymJ>. Innafa 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 (Lapland, Små. 

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



43. C. (Encyonema) iiorvegica Grun. (1875). — V. asymmetrical, liuear, with obtuse, 

 broad ends. L. 0, 04 to 0,0.5; B. 0, 007 to 0,oo8 mm. Median line straight, nearly axial, with the 



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



