186 p. T. CLEVB, SYNOPSIS OF THE NAVICULOID DIATOMS. 



27. C. naviculiformis Aueusw. (1861). — V. elliptic-lanceolate, slightly asymmetrical, with 

 rostrate-capitate ends. L. 0,03 to 0,o4 7; B. 0,oi to 0,oi6 mm. Median line almost central, nearly 

 straight. Axial area narrow, linear, suddenly dilated in the middle to an orbicular space. Striae 

 in the dorsal side 14 (middle) to 18 (ends) in 0,oi mm., on the ventral side 14 in 0,oi mm. 

 — AuBRSw. Rabh. Alg. E. N:o 1065. V. H. Syn. PI. n f. 5. C. cuspidata W. Sm. B. D. I PI. II 

 f. 22 a'. G. anglica Lagst. Spitsb. D. p. 42 PI. II f. 18 (1873). A. S. Atl. IX f. 63. V. H. Syn. 

 PL II f. 5. 



Fresh water: Grreenland! Spitsbergen! Beeren Eiland (Lagst.), Norway (Eomsdalen, Dovre)! 

 Sweden! Finland! Holstein! Harz (Atl.), Jenissey! New-Zealand! Australia! 



Heiberg (Consp. Grit. p. 108) remarks that Cymb. cuspidata W. Sm. is not the species of 

 KuTziNG, but possibly C. navicuUformis, of which he gives several figures (PI. 1 f. 3), which 

 however are much more similar to C. ampMcephala than to this species. Lagerstedt proposed the 

 name C. anglica, believing it to be identical with the species of W. Smith, which is too indistinctly 

 figured for identification. C. naviculiformis closely resembles C. amphicephala, from which it is 

 distinguished by the larger central area. 



28. C. hybrida Grun. (1878). — V. linear, almost symmetrical, with rostrate ends. L. 

 0,04 5; B. 0,0 09 mm. Median line almost central and straight. Axial area narrow; central area 

 large, subquadrate. Strise 11 in 0,oi mm. almost parallel, finely punctate. — GrRUN. in CI. M. D. 

 N:o 161. Icon, nostr. PI. IV f. 23. 



Fresh or very slightly brackish water: Sweden (Gothland, Lefrasjon in Skane)! 



29. C. spuria Cl. N. Sp. — V. asymmetrical, lanceolate, with subrostrate ends. L. 0,o5 

 to 0,06; B. 0,013 mm. Median line very slightly arcuate, almost central. Axial area narrow, 

 gradually dilated towards the middle. Strise 12 (dorsal, median) to 13 (ventral and dorsal, termi- 

 nal) in 0,0 1 mm., slightly radiate in the middle, almost parallel in the ends, finely but distinctly 

 punctate. 



Fresh water: Talbot (Victoria, Australia)! Pichinicha (alpine region of Ecuador)! 



30. C. cuspidata Kutz. (1844). — V. broadly linear-lanceolate, slightly asymmetrical, with 

 rostrate-capitate ends. L. 0,o4 to 0,095; B. 0,oi4 to 0,024 mm. Median line slightly excentric, 

 straight. Axial area narrow, linear; central area rather large, orbiciTlar. Strife 9 or 10 (middle) 

 to 12 or 14 (ends) in 0,oi mm. radiate, finely lineate. — Kutz. Bac. PI. Ill f 40. Heib. Consp. 

 p. 109 PL I f. 4. A. S. Atl. IX f. 50 (typical) 53 to 55. V. H. Syn. p. 61 PL II f. 3. 



Fresh water: Sweden (Lappland to Upsala and Westergotland) ! Norway (Finmark, Dovre)! 

 Finland! Paris! Belgium (V. H.), England! Germany! Italy! Greenland! Canada! Massachusetts! 

 Jenissey! Kamtschatka! Japan! New Zealand! 



Var. ohtusiuscula Grun. (in V. H. Types N:o 19). — L. 0,06 to 0,o8; B. 0,oi9 to 0,02 mm. 

 Ends more rounded. 



Fresh water: England (V. H. T.). 



31. C. heteropleura Ehb. (1843). — V. slightly asymmetrical, lanceolate, with rostrate 

 and truncate to subrostrate, obtuse ends. L. 0,i2 to 0, 15; B. 0,033 to 0,04 mm. Median line 

 almost central, straight. Axial area distinct, linear. Central area large, slightly transversely 

 dilated. Strise 9 to 10 in 0,oi mm. slightly radiate throughout, punctate; puncta 9 to 13 in 0,oi 

 mm. — Pinnularia heteropleura Ehb. Am. p. 133. M. G. V: 2 f. 11. Cymb. het. KtiTZ. Bac. p. 79. 

 A. S. Atl. IX f. 4, 5. 



Fresh water (arctic and northern regions): Greenland! Norway (Dovre)! Sweden (Lappland)! 

 Russian Lappland! 



