62 p. T. CLEVE, SYNOPSIS OF THE NAVICULOID DIATOMS. 



Var. africana Cl. — V. elliptic-linear, with broad and rounded ends. L. 0,i3; B. 0,2 5 mm. 

 Longitudinal lines crossing the strise in their middle. Striae 15 in 0,oi mm. — PI. IV f. 5. 

 Brackish water: Cameroon! 

 The var. africana merits perhaps to be considered as a distinct species. 



50. C. Holstii Cl. (1881). — V. elliptical, with parallel margins and cuneate ends. L. 0,o52 

 to 0,06; B. 0,016 to 0,02 mm. Axial area very narrow; central area small, rounded. Strife 14 in 

 0,01 mm. almost parallel, not distinctly or finely punctate. Longitudinal lines marginal. — A. S. 

 Atl. L. f. 48 (without name). Nav. Holstii Cl. D. f. Gronl. and Argentina p. 11 PL XVI f. 1. 



Fresh water: Greenland! Albany, Maine, fossil! Oregon (Atl.). 



51. C. Ladogensis Cl. (1891). — V. broad, lanceolate, with subrostrate ends. L. 0,025; 

 B. 0,0 14 mm. Axial area indistinct; central area small rounded, somewhat transverse. Striae 17 

 in 0,01 mm. slightly radiate, finely punctate. Longitudinal lines marginal, faint. — Nav. Ladog. 

 Cl. D. of Finl. p. 35 PI. II f. 3. 



Fresh water: Ladoga, on the surface of the lake! 



52. C? dispersa Gr. and Stdrt (1887). — V. almost flat, elliptic-lanceolate, with subacute 

 ends. L. 0,08; B. 0,027 ram. Median line straight, terminating close to the margin. Axial area 

 narrow, dilated in the middle to a small rounded space. Striae 27 in 0,oi mm., finely punctate, 

 piincta forming undulating longitudinal lines. The striae are confined to an irregular, lanceolate 

 space aroiind the axial area, the part outside of this space being irregularly and coarsely punctate. 

 Longitudinal lines inframarginal. — Nav. disp. Gr. and Stcrt. Queck, M. Cl. Ill (2) p. 132 

 PL X f. 10. 



Marine: Oamaru, N. Zeeland, fossil! 



This is remarkable species, which I have placed here only with hesitation. The longi- 

 tudinal] line is visible only in strongly oblique light. A somewhat] similar form occurs at 

 Monterey, which 1 know by a sketch sent by Grunow, who calls it Mastogloia? decorata. This 

 form is smaller (L. 0,033; B. 0,oi3 mm.) and has a larger quadrate central area and probably 

 coarser striae. 



53. C? sejiincta A. S. (1874). — V. linear, with parallel margins and rounded cuneate 

 ends. L. 0,o4; B. 0,oi mm. Axial and central areas indistinct. Striae 12 in 0,oi mm. transverse. 

 Longitudinal lines broad, submarginal. — Nav. sejuncta A. S. N. S. D. p. 87 PI. If. 18. 



Marine: North Sea, Campeachy Bay (A. S.). 



I have not seen this species, which A. Schmidt seems to consider akin to Diploneis 

 nitescens. It seems to me more probable that it belongs to the group of C. Powellii. No indica- 

 tion of the nature of the striae exists. If punctate this form may be a Diploneis; if smooth it 

 belongs to the group of C. Powellii. 



54. C. blanda A. S. (1874). — V. linear, with rounded ends. L. 0,o5 to 0,13; B. 0,oi to 

 0,018 mm. Axial area narrow. Central area orbicular, large. Striae 8 to 10 inO,oi mm. parallel, 

 radiate at the ends, not distinctly punctate. Longitudinal lines broad. — Nav. blanda A. S. N. 

 S. D. p. 90 PL II f. 27. Finn, ergadensis Grb». T. M. S. 1856 p. 48 PL V f. 22? 



Marine: North Sea! Black Sea! Ceylon! Seychelles! Amboina! Labuan! Tahiti! 



55. C, supergradata Brun. (1891). — V. convex, linear, with rounded ends. L. 0,115 to 

 0,135; B. 0,016 mm. Axial and central areas combined in a broad, linear space. Median line 



strongly flexuose. Striae 6 in 0,oi mm., parallel smooth. Longitudinal lines broad, marginal. 



Nav. super gr. Brun. D. Esp. n. p. 40 PL XV f. 6. 



Marine: Gulf of Naples! Port d' Alger (Brun), Bosphorus (Brun). 



