KONCiL. SV. VET. AKADKMIKNS II ANDLI N(i AI{. HAND 26. N:() 2. \^t^ 



in (1,0 1 mm., slightly radiate tlirougliout, distinctly pvuictate. No iscdated punctum bidow the 

 central nodule. — Grun. in Martelli Florula Bogosensis p. 152 PI. 1 f. 1, 2. 

 Fresh water: Abyssinia (Grun.). 



54. €. Cistulsi Hemph. (182«). — V. boat-sliaped, with concave,, centrally slightly gibbous, 

 ventral margin, and truncate or rounded, obtuse ends. L. 0,07 to 0, le; B. 0,oi8 to 0,o'2.'j mm. 

 Median line arcuate, broad, bent downwards near the central nodule. The central pores distant, 

 and the terminal fissures reflexed. Axial area narrow, linear, slightly dilated on the dorsal side 

 of the central nodule. Stria' 7 to 9 in 0,0 1 mm. coai'sely lineate; lineohr, 1?S to 21 in 0,oi mm. 

 On the ventral side, near the central nodule, the strisB are interrupted by a narrow depression, so 

 that beloAV the central nodule is a segmental row of 2 to 5 puncta. — Bacilluria Cistula Hempk. 

 a. Ehb. Symb. Phys. phyto. PI. II, IV f. 10. Coccon. Cistula W. Sm. B. I). XXIII f. 221. A. S. 

 Probet. f. 1(5 PI. X f. 1—5, 24—26. Cijmh. Cistula V. H. Syn. p. 64 PI. II f. 12—13. C. Cistula 

 var. mneidata A. S. Atl. LXXI f. 21. Grun. Franz Josephs Land D. p. 97 (45) PI. I f. 8. C. Cistula 

 var. fusulium H^rib. a. Perag. D. d'Auvergne p. 71 PI. Ill f. 12. Coccon. arcticum A. S. Atl. 

 LXXI f. 25. Coccon. cornutum Greg. M. J. IV PI. If. 11 (1856)? 



Fresh and slightly brackish water: Spitsbergen! Norway (Dovre, Stavanger, foss.)! Sweden 

 (Lapland to vSkane), Bay of Bothnia (from Pitea to Uppland and Helsingfors)! Finland! England! 

 Holstein! Belgium! France! Germany! Switzerland! Italy! Mouth of Jenissey! Kamtschatka! Japan! 

 Yarkand! America (Winnepeg, Vancou.ver, Massachusets, Illinois, California, Mexico)! 



Var. maculata Kiixz. (1834). — V. broader and shorter than in the type. L. 0,045 to0,082; 



B. 0,013 to 0,015 mm. Strifx; 9 to 12 in 0,oi mm. Lineobe 24 in 0,oi mm. No row of puncta 

 below the central nodnle. — Frustulia maculata KtJTZ. Dec. N:o 85 (1834) according to Lagst. 

 Cijmh. maculata A. S. Atl. X f. 6; LXXI f. 20, 22. Cymh. Cistula var. mac. V. H. Syn. p. 64 

 PI. II f. 16, 17. Cymh. Bonleana Br. a. H^rib. D. d'Auvergne p. 220 PI. VI f. 14 1893 (ad spec, 

 auth.). Cymh. Pauli H^rib. a. Perag. D. d'Auvergne p. 70 PI. Ill f 11 (1893). 



Fresh water: Franz Josephs Land (Grun.), Spitsbergen! Sweden (Vestergotland, Smaland)! 

 Finland! England! France! Germany! Greenland! Argentina! 



Var. sibirica Grun. (1880). — V. with rounded, not rostrate ends. L. (),o8; B. 0,o24 mm. 

 Median line strongly arcuate. Strire 10 (middle) to 12 (ends) in 0,oi mm. lineate (lineolai about 

 20 in 0,0 1 mm.) interrupted in the ventral side of the central nodule by a narrow depression. — 

 Coccon. Cistula var. sih. Grun. A. D. p. 25 PL I f. 11. 



Fresh water: Mouth of Jenissey! 



Var. arctica LA(iST. (1873). — V. boat-shaped, with strongly arcuate dorsal, and slightly 

 concave ventral, margin. Ends truncate. L. 0,o32 to 0,o7; B. 0,oo7 to OjOi.'j mm. Median line strongly 

 arcuate, broad; its terminal fissures reflexed. Axial area narrow. StritU 9 to 13 in 0,oi mm. 

 finely lineate. No row of puncta on the ventral side of the central nodule. — Cymh. variahilis 

 var. arctica Lagst. Spitsb. I), p. 44 PI. II f. 21. Cymh. arctica A. S. Atl. X f. 12; LXXI f. 23, 24. 



Fresh water: Beeren Eiland (Lagst.), Spitsbergen! Russian Lapland! Mouth of Jenissey! 



Var.? frioicata Brun (1880). — V. with slightly arcuate dorsal margin, straight ventral margin 

 and very ])road, truncate ends. L. 0,04 5 to 0,o7 5 mm. Stri;xj 8 to 10 in 0,oi mm. No row of 

 puncta l)elow the central nodule. — Brun D. des Alpes p. 58 PI. Ill f. 2. 



Fresh water: Switzerland (Brun.). 



C. Cistula is a very variable species, graduating, as it appears, to C. cymhiformis. Its most 

 distinctive characteristic, the row of puncta below the central nodule, is not present in some of 

 its varieties. The var. '^ truncata is remarkable for its outline and resembles very much the smaller 



C. curta A. ScHM. (Atl. IX f. 47. L. 0,02; B. (),oi mm.) unknown to me. 



55. C. Stiixbergii Cl. (1880). — V. with strongly arcuate dorsal margin, almost straight 

 ventral margin, and rostrate, truncate ends. L. OjO.'is to 0,o75; B. 0,02 mm. Median line strongly 

 arcuate, with retlexed terminal fissures. Axial area indistinct, slightly dilated on the dorsal side 



