KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 26. N:0 2. 51 



21 in 0,01 mm. parallel. Longitudinal lines faint, median. — Nav. Bcccariaria Grun. in Martelli 

 Flomla Bogosensis p. 153 Pl. I f. 5. Cal. B. Icon. n. Part. ]I Pl. 1 f. 7. 

 Brackish water: Calcutta! Abyssinia (Grun.). 



5. C. Clevci Lägst. (1873). — V. convex, linear, with broad, subrostrate ends. L. 0,0 5 2 to 

 0.065; B. 0,011 to 0,014 mm. Axial area indistinct; central area a transverse fascia. Strise 24 in 

 0,01 mm. (17,5 to 20 according to Lagbkst.) slightly convergent in the middle and at the ends. 

 Longitudinal lines distinct, submaxginal. — Nav. Cl. Lägst. Spitsb. D. p. 34 Pl. I f. 10. 



Fresh water: Spitsbergen! 



6. C. cohimbiensis Cl. N. Sp. — V. elongated, biconstricted, with cuneate ends. L. 0,044 ; 

 B. 0.007 mm. Axial area narrow, somewhat broader in tlie middle, between the central nodule and 

 the ends. Central, area a broad, transverse fascia. StritE almost parallel, 19 in 0,oi mm. Longi- 

 tudinal lines indistinct. — Pl. III f. 34. 



Fresh water: Columbia Eiver, Oregon (Weissflog Coll.!) 



I am unable to identify this form with any other, and it seems douljtful whether it belongs 

 to this group of Navicula or to Pinnularia. 



7. C. lobafa Schwärtz (1877). — V. small, short and stout, biconstricted, with broad, 

 rounded-truncate ends. L. 0, 03; B. 0,oi5 mm. Axial area narrow linear. Striaä line, crossed by 

 a median, longitudinal line. — Nav. lohata Schw. in Rab. A. E. N:o 2481 (with fig.). 



Marine? Vera Cruz. 



I have not found this species in N:o 2481 of Rab. Dec. for which reason I am unable to 

 decide if it be the same as Nav. lohata in Cl. West. Ind. D. p. 7 Pl. I f. 8. They agree in size 

 and outline but on the West Indian form no longitudinal lines have been observed. 



8. C. Siliciila Ehb. (1843). — V. elongated, gibbous in the middle with more or less clavate, 

 obtuse ends. L. 0,033 to O, os; B. 0,oo6 to 0,oi5 mm. Axial area indistinct or narrow; central 

 area small and rounded, or a broad transverse fascia. Strire 16 to 18 in 0, 01 mm. almost parallel 

 or slightly divergent in the middle and at the ends. Longitudinal lines mai'ginal. 



A. Forms with small central area. 



Var. alpina Cl. - V. small, gibbous in the middle. L. 0,033 to 0,042; B. 0, 0055 to 0,oo75 

 mm. Axial area indistinct; central area very small. Strite 19 to 22 in 0,oi mm. — Nav. liniosa 

 Lagbrst. Spitsb. D. Pl. I f. 6. Nav. Silicula Grun. in V. H. Syn. Pl. XII f 21. 



Fresh water: Spitsbergen! Norway, i)ovre! Rnssian Lapland! Sweden, Arbrä, Helsingland! 

 Greenland! 



Var. gibberula Kutz. — V. gibbous in the middle, with subcuneate ends L. O, o 5 to 0,os; B. 

 0,01 to 0,015 mm. — Nav. gibhrnila KtJTZ. Bac. Pl. III f. 50 (1844). W. Sm. B. L. I Pl. XVII 

 f. 160. Nav. limosa Kutz Bac. p. 101 Pl. III f. 50 (1844). Donk. B. D. Pl. XII f. 6 b. Nav. 

 liniosa gcmiina Grun. Verh. 1860 Pl. V f. 8 b. Nav. limosa v. gibicrula V. H. Syn. Pl. XII f. 19. 



Var. genuina Cl. -■ V. slightly gibbous in the middle, with subclavate, rounded ends. L. 

 0,05 to 0,08; B. 0,0 15 mm. Axial area narrow. — Nav. Silicula Ehb. Am. p. 131. M. G. VI, 1 

 f. 16 etc. Nav. limosa Donk B. D. Pl. XII f. 6 a. V. H. Syn. Pl. XII f. 18. 



The var. gibberula and genuina are very slightly different and graduate into each other 

 completely. They occur in fresh, sometimes slightly brackish water: Sweden! Finland! England! 

 Germany! Belgium (V. H.) Switzerland! Greenland! N. America! New Zealand! 



Var. unclulata Grun. (1880). — V. elliptical, with very slightty undulated margin L. 0,0 5; 

 B. 0,013 mm. — Nav. limosa v. unclulata Grun. V. H. Syn. Pl. XII f. 22. 



Var. infläta Grun. (1860). — V. elliptical-linear, very slightly gibbous in the middle. L. 

 0,05; B. 0,011 mm. — N. lim. var. infläta Grun. Verh. 1860 Pl. V f. 8 c. N. limosa var. szibinfl. 

 Grun. V. H. Syn. Pl. XII f. 20. 



