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



Var. dcrasa Grdn. (1880). — Strife crossed on each side by a more or less narrow lateral area. 

 L. 0,05.5 to 0,067; B. 0,oi45 to 0,01.5 mm. Striae 8,5 or 12 (middle) to 10 or 14 (ends)inO,oi mm. 

 — .V. derasa Grun. A. D. p. 39 PI. II f. 46. N. trans, v. derasa Cl. Vega p. 467 PI. XXXVI f. 32. 



Marine: Sea of Kara! Cape Wankarema! Cape Deschneff! 



Forma minuta. — L. 0,035; B. 0,oi2 mm. Striae 12 in 0,oi mm. — Cl. Vega p. 467 

 PI. XXXVI f. 37. 



Marine; Cape Deschneff! 



Forma gracilenta GtRUN. (1880). — V. narrower, with prolonged ends. L. 0,o65 to 0,o75; 

 B. 0,009 to 0,01 1 mm. Striae 10,5 to 11 in 0,oi mm. — N. derasa var.? gracilenta Grun. A. D. p. 40. 



Marine: Sea of Kara (Grun.). 



Var. incudiformis Grun. (1883). — Axial area unilateral, irregular, linear. Striae on the 

 side, opposite to the axial area, crossed by a more or less broad lateral area, usually uniting with 

 the central area. — N. incus v. abbreviata Grun. A. D. p. 39 PI. II f. 43. N. incudiformis Grun. 

 in Cl. Vega p. 467 PI. XXXVI f. 26, 30. 



Marine: Cape Wanharema! 



Var. erosa Cl. 1883. — Striae 7,5 to 10 in 0,oi mm., crossed by several narrow, undulating, 

 longitudinal bands. — N. erosa Cl. Vega p. 468 PI. XXXVI f. 28. 



Marine: Cape Wankarema! 



Var. asymmetrica Cl. (1883). — Axial area unilateral, irregularly linear. Striae 9,5 in 0,oi 

 mm. as in var. erosa. — N. asymmetrica Cl. Vega p. 468 PI. XXXVI f. 27. 



Marine: Cape "Wankarema! 



55. N. flnmarchica Cl. a. Grun. (1880). — V. lanceolate, with obtuse ends. L. 0,0 3 to 

 0,04 2; B. 0,0115 to 0,013 mm. Central nodule transversely dilated to a short stauros. Striae 12 

 to 14 in 0,0 1 mm., slightly radiate, apparently smooth, crossed by a narrow, arcuate lateral area. 

 "- Stauroneis finm. Cl. a. Grun. A. D. p. 47 PI. Ill f. 63. 



Marine: Finmark! Bohuslan! 



It is difficult to find the proper place in the system for this little form. There is no 

 allied species in Stauroneis, nor any other naviculoid form, to which it seems to be related, with 

 the exception of N. transitans var. derasa f. minuta, from which it differs by its stauros and 

 apparently smooth striae. This form is neither a Mastogloia nor an Achnanthes, both valves 

 being similar. 



56. N. kariana Grun. (1880). — V. broadly lanceolate, slightly rostrate. L. 0,o85 to0,09; 

 B. 0,0 24 to 0,0 2 6 mm. Median line with approximate central pores. Axial area indistinct; central 

 area small, orbicular. Striae 12,5 to 14 in 0,oi mm., parallel, finely lineate ; lineolae forming longi- 

 tudinal striae, about 27 in 0,oi mm. — A. D. p. 39 PL II f. 44. 



Marine: Frans Josefs Land! Sea of Kara! Cape Wankarema! 



Var. detersa Grun. (1883). — Striae crossed by a more or less large lateral area. — Cl. 

 Vega p. 469 PI. XXXVI f. 36. Franz Jos. Land D. p. 103 PI. I f. 23, 24. 



Marine: Franz Josefs-Land (Grun.), Cape Wankarema! 



Var. frigida Grun. (1880). — L. 0,044 to 0,o7; B. 0,oi2 to 0,oi3 mm. Striae 15 or 16 

 (middle) to 17 or 18 (ends) in 0,oi mm. very slightly radiate throughout, finely lineate; lineolae 

 forming longitudinal striae, about 26 in 0,oi mm. — A. D. p. 39. Franz Jos. Land D. p. 103 

 PI. I f. 25. 



Marine: Sea of Kara! Franz Josefs-Land! 



57. N. gelida Grun. (1884). — V. lanceolate, with slightly rostrate ends. L. 0,03 toO.oes; 

 B. 0,009 to 0,015 mm. Axial area indistinct. Central area very small, orbicular. Striae 9 to 12 

 in 0,01 mm., finely lineate; lineolae not forming longitudinal striae. — Franz Jos. Land D. 

 p. 103 PI. I f. 27, 28. N. Mriana v. curta Cl. Vega p. 470 PI. XXXVII f. 40 (1883). 



Marine: Davis Strait! Franz Josefs-Land (Grun.), Cape Wankarema! Cape Deschneff! 



