26 P. T. CLEVE, SYNOPSIS OF THE NAVICULOID DIATOMS. 



Marine: Greenland! Spitsbergen! Finmark! Sea of Kära! Cape DeschnefF! Behrings Island! 

 Japan, fossil! Pacific Ocean (Grrun.). 



N. Bolleana has somewhat dissimilar valves, the concave having more strongly radiate strise 

 than the convex. Original specimens of Nar. Index Temp. a. Brun are perfectly similar to 

 specimens of N. Bolleana, determined by Grunow. 



45. N. incerta Urun. (1880). — V. linear, with slightly convex margins and obtnse ends. 

 L. 0,015; B. 0,006 mm. Axial and central areas indistinct. Strise 15in0,oi mm., scarcely radiate. 

 — V. H. Syn. p. 107 Pl. XIV f. 43. 



Marine: Belginm (V. H.). 



A small form, remarkable for its coarse striee, unknown to the anthor. Its place in the 

 system is doubtful. 



46. N. (Schizonema) corymbosa C. Ag. (1824). V. narrow, lanceolate, obtnse. L. 0,oi; 

 B. 0,002 mm. Axial and central areas indistinct. Stria; 23 in 0,oi mm. very slightly radiate. — 

 Sehisonema corymbosum Ag. Syst. Alg. p. 11. V. H. Syn. Pl. XVI f. 21. 



. Marine: Japan (Grun.). 

 The frustules live in hair-fine branched tnbes. 



47. N. (Schizonema) mollis W. Sm. (185fi). — V. lanceolate, obtiise. L. 0,027 to 0,0^2; 

 B. 0,006 to 0,007 mm. Axial and central areas indistinct. Strise 14 to 16 in 0, 01 mm. radiate in 

 the middle, elsewhere parallel, finely lineate; lineolse forming longitndinal strise. — Schizon. molle 

 W. Sm. b. D. n p. 77 Pl. LVIII f. 365. V. H. Syn. Pl. XV f. 22, 23. S. alhieans V. H. Syn. 

 1. c. f. 20. S. torquatum V. H. Syn. 1. c. f. 21. 



Marine: Arctic Amercia, Cape Sabine! Bohuslän! North Sea! Adriatic! 



The frustules are crowded in very branched, soft tubes, forming branches 15 to 30 cmt. long . 



A form intermediate between N. mollis and N. ramosissima is S. setacemn V. H. Syn. XV 

 f. 13. The frustules of this form live crowded in stiff, olive-green coloured, arborescent and very 

 branched tubes. 



48. N. (Schizonema) nidulans Cl. (1892). — V. narrow linear-lanceolate. L. 0,o26; B. 0,oo5 

 mm. Axial and central areas indistinct. Strige 22 in 0,oi mm., parallel. Frustules inhabit the 

 interiör of marine algse. — Cl. Diatomiste I p. 78 Pl. XII f. 12. 



Marine; South coast of Australia, in the thallvis of a Chylocladia, sent by Prof. J. Agardh ! 



49. N. (Schizonema) ramosissima Ag. (1824). — V. linear-lanceolate, with obtuse ends. 

 L. 0,o.'ii to 0,072; B. 0,01 to 0,008 mm. Axial and central areas indistinct. Strise 12 to 13 in 

 0,01 mm. parallel, finely lineate, lineolte forming longitndinal strise, about 30 in 0,iii mm. 



Forma caspia Grun. (1878). — L. O.o.'?» to 0,052; B. 0,007 to 0,no8 mm. Strise 12 in 0,01 

 mm. — Casp. Sea Alg. p. 19 Pl. IV f. 21. 



Brackish water: Caspian Sea (Grun.). 



Forma genuina Cl. — L. about 0,o5 mm. — Schiz. ram. C. A. Syst. Alg. p. 11. V. H. 

 Syn. p. 110 PL XV f. 4, 5. 



Marine: North Sea! 



Forma amplia Grun. (1880). — L. 0,o6 to 0,072; B. 0,007 to 0,oo8 mm. Strise 10 to 12 in 

 0,01 mm. - Schizon. amplius V. H. Syn. Pl. XV f. 3. — A. S. N. S. I). III f. 5. 



Marine: North Sea! Canada! Mauritius! 



N. ramosissima lives enclosed in gelatinons tubes on the various forms of which a great 

 nniiiher of species and varieties has been founded (see Grunow's paper in Botan. Centralbl. 1880). 

 As mentioned above, this species is iiearly akin to N. mollis, and on the other liand to smaller 

 forms of A. directa var. subtilis, from which iV. raiiM.sis.<iiiiia can scarcely be distinguished. 



