KONCL. SV. VET. AKADEMIKNS IIANDLIN(!AI{. HANI) 26. N:() 2. 51 



^1 ill 0,0 1 inrn. parallel. Jwongitudinal lines faint, median. — Nav. Bcrcdriniia (tkiin. in Martelli 

 Florida Bogosensis p. ir)3 PI. 1 f. 5. Cal. B. Icon. n. Part. ]1 PL 1 f. 7. 

 Brackish water: ('alcntta! Abyssinia (Grun.). 



5. C. Clevei Lagrt. (1873). — V. convex, linear, witli broad, .sulirostrate ends. L. (},(n,2 to 

 O.oe.'i; B. 0,0 11 to 0,oi4 mm. Axial area indistinct; central area a transverse fascia. iStri;e, 24 in 

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

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



Fresh water: Spitsbergen! 



<). ('. coluiubiensis Cl. N. Sp. — V. elongated, biconstricted, with cuneate ends. L. 0,o44; 

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

 the ends. Central area a broad, transverse fascia. 8tritE almost parallel, 19 in 0,oi ram. Longi- 

 tudinal lines indistinct. — PI. Ill f. 34. 



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



I am nnable to identify this form with any other, and it seems doubtful whether it lielongs 

 to this groiip of Navicula or to Pinniilaria. 



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

 rounded-truncate ends. L. 0,0:3; B. 0,01,5 mm. Axial area narrow linear. Stria' 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 whichi reason I am unable to 

 decide if it be the same as Nar. lohafa in Cl. West. Ind. D. p. 7 PI. 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,o33 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. Strife, 16 to 18 in 0,oi mm. almost parallel 

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



A. Forms ivifh small central area. 



Var. alpiua 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. StriiB 19 to 22 in 0,oi mm. — Nav. limosa 

 Lagbrst. Spitsb. D. PI. I f. 6. Nav. Silicula GtRUN. in V. H. Syn. PI. XII f. 21. 



Fresh water: Spitsbergen! Norway, Dovre! Ilussian Lapland! Sweden, Arbra, Helsingland! 

 Greenland! 



Var. gihberula Kutz. — V. gibbous in the middle, with subcuneate ends L. 0,o5 to 0,o8; B. 

 0,01 to 0,01.5 mm. ^ Nar. gibberula KtJTZ. Bac. PI. Ill f. 50 (1844). W. Sm. B. i). I PI. XVII 

 f. 160. Nav. limosa Kutz Bac. p. 101 PI. Ill f. 50 (1844). Donk. B. D. PL XII f. 6 b. Nav. 

 limosa (jenuina Grun. Verb. 1860 PL V f . 8 b. Nav. limosa v. gibberida 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. 0,015 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 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. wululata Grun. (1880). — V. elliptical, with very slightly undulated margin L. 0,o5. 

 B. 0,0 13 mm. — Nav. limosa v. undulata Grun. V. H. Syn. PL XII f. 22. 



Var. inflata Grun. (1860). — V. elliptical-linear, verj' slightly gibbous in the middle. L. 

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

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



