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



,, j Median line sigmoid 10. 



' '[ — — straight • 13. 



I Valve with an annulus at the side of the centre C. cydopJiora Grun. 



) — without 11. 



..^ j Strise of the upper valve coarse ('J to 11 in O.oi mm.) 12. 



\ — — — — fine (25 — — — ) - . C. heteroidea Hantscu. 



^,. j Central nodule transversely dilated C. arctica Cl. 



^ \ — — not — — C. vohita Br. 



..., j Lateral areas connected to a broad marginal annulus 14. 



1 — - not — — — — - 15. 



. , ) Strite of the upper valve cora])osed of coarse puncta C. antiqua Br. 



\ — — — — costate with a median punctum (,'. interru'pta Grun. 



I Upper valve with longitudinal furrows or depressions 16. 



15. 



without 18. 



..,, j With several, strong furrows C. pellucida Hantsch. 



1 — — a lunate depression 17. 



.„ j Stria! fine (16 to 31 in 0,oi mm.) punctate C. pseudoviarfjinata Greg. 



) — coarse (10 in O.oi mm.) costate, with a median punctum C. vitrea Brun. 



^„ J Lateral areas crossed by two oblique rows of puncta C. prcecellens Pant. 



' \ — — not — — — — — — C. Letourneuri Cl. 



1. €. molest.a (Kiixz. 1844) Grun. (1881). — Otitline elliptical, with broad, rounfled ends. 

 L. U,()i7 to 0,(119; B. 0,007 to 0,oo8 mm. Upper V. with narrow axial area. Stria; more tliau oO 

 in 0,0 1 mm. finely punctate, puncta forming zig-zag-lines. Lower V. with straight median line, 

 not reaching to the end.s. Central area very small. Strite more than 30 in 0,o i mm. punctate, puncta 

 forming fine, longitudinal strict. — Bac. p. 71 PI. V f. 7, 11, 12. V. H. Syn. PI. XXX f. 18, 19. 

 A. S. N. S. D. PI. Ill f. 20? 



Marine: Venice (Klitz.). 



Var. crucifcra GriiUN. (1881). — L. 0,oi5 to 0,o2.^; B. 0,oo8 to O.oig mm. Central area of 

 the lower valve dilated to a transverse fascia. — V. H. Syn. PI. XXX f. 20, 2o. C. diaphana 

 W. Sm. B. D. p. 22 PL XXX f. 254 (partim) 1853. A. S. Atl. CXCIII, 48 to 51. 



Marine: England! Coasts of France! 



Var. amygdalina (Br^b.) Grun. (1881). — L. 0,o.35 to 0,04 5; B. 0,oi3 to 0,02 mm. Upper 

 V. with about 20 strise in 0,oi mm. Lower V. with slightly dilated central area and about 27 

 strige in 0,oi mm. -- C. diapltana W. Sm. B. D. I p. 22 PI. XXX f. 254 (partim). C. aniyydulina 

 Grun. in V. H. Syn. XXX f. 5. 35. 



Marine: French coast of the English Channel! 



2. C. fiiiiuarcliica Grun. (1880). — Elliptical. L. 0,012 to O.oio; B. 0,oo5.^) to 0,oo7 mm. 

 Upper V. with linear axial area. StriiB 20 in 0,oi mm. slightly radiate. Lower V. with straight 

 juedian line, ending near the margin. Central area a fascia, not reaching to the margin. Strite 24 

 in 0,01 mm. slightly radiate. — A. D. p. l(i PI. I f. 1. 



Marine: Arctic America! Finmark! 



3. (I. septentrioiiiilis Grun. (1884). — Elliptical. L. 0,022 to 0,o.'36; B. 0,012 to 0,023 mm 

 Upper V. with narrow axial area. Strite 8 in 0,oi mm. almost parallel, punctate; puncta 14 in 

 0,01 mm., larger at the margin, not arranged in longitudinal rows. Lower V. with straight 

 median line. Central area a narrow, transverse fascia. Striae radiate, !• in <),oi mm. punctate; 

 ])uncta 1() in 0,oi mm. — Franz Josefs Land JJ. p. 55 PI. 1 f. 2. 



Marine: Assistance Bay (Grun.). 



4. A. Calcsir Cl. (1891). — Broadly elliptical. 1j. 0,012; B. 0,oo',) mm. Upper V. with 

 straight, narrow axial area. Central area on one side of the nodule dilated into a spurlike pro- 

 jection, on the other bifid, forming an horseshoe-like marking. Lower V.(?) with straight median 



