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



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

 Florula Bogosensis p. 153 PL I f. 5. Cal. B. Icon. n. PI. VI f. 7 (Part. 11 PL I f. 7). 

 Brackish water: Calcutta! Abyssinia (G-run.). 



5. C. Clevei Lasst. (1873). — V. convex, linear, with broad, subrostrate ends. L. 0,o.52 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 Lagekst.) slightly convergent in the middle and at the ends. 

 Longitudinal lines distinct, submarginal. — Nav. CI. Lagst. Spitsb. D. p. 34 PL I f. 10. 



Eresh water: Spitsbergen! 



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

 B. 0.00 7 mm. Axial area narrow, somewhat broader in the middle, between the central nodule and 

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

 tudinal lines indistinct. — PL III f. 34. 



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



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

 to this group of Navicula or to Pinnularia. 



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

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

 a median, longitudinal line. — Nav. lobata 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. Silicula Ehb. (1843). — V. elongated, gibbous in the middle with more or less clavate, 

 obtuse ends. L. 0,033 to 0,o8; B. 0,oo6 to 0,oi5 mm. Axial area indistinct or narrow; central 

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

 or slightly divergent in the middle and at the ends. Longitudinal lines marginal. 



A. Forms with small central area. 



Var. alpina Cl. — V. small, gibbous in the middle. L. 0,033 to 0,042; B. 0,oo55 to 0,oo75 

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

 Lagbrst. Spitsb. D. PL I f. 6. Nav. Silicula Grun. in Y. H. Syn. PL XII f. 21. 



Fresh water: Spitsbergen! Norway, I)ovre! Russian Lapland! Sweden, Arbra, Helsingland! 

 Greenland ! 



Var. gihherula Kutz. — V. gibbous in the middle, with subcuneate ends L. 0,05 to 0,o8; B. 

 0,01 to 0,015 mm. — Nav. gibberuJa KtJTZ. Bac. PL III f. 50 (1844). "W. Sm. B. D. I PL XVII 

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

 limosa genuina Grun. Verh. 1860 PL V f. 8 b. Nav. limosa v. gibberula V. H. Syn. PL XII f. 19. 



Var. genuina Cl. — V. slightly gibbons in the middle, with subclavate, rounded ends. L. 

 0,05 to 0,08; B. 0,015 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 difPerent 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. undulata Grun. (1880). — V. elliptical, with very slightly undulated margin L. 0,o5. 

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



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

 0,05; B. 0,011 mm. — N. lim. var. inflata Grun. Verh. 1860 PL V f . 8 c. N. limosa var. suhinfl. 

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



