26 p. T. CLEVE, SYNOPSIS OF THE NAVlOULOID DIATOMS. 



Marine: Greenland! Spitsbergen! Finmark! Sea of Kara! Cape Deschneff! Behrings Island! 

 Japan, fossil! Pacific Ocean (Grun.). 



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

 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 Grun. (1880). — V. linear, with slightly convex margins and obtuse ends. 

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

 - V. H. Syn. p. 107 PL XIV f. 43. 



Marine: Belgium (V. fl.). 



A small form, remarkable for its coarse striffi, unknown to the author. Its plac6 in the 

 system is doubtful. 



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

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

 Srhizonema corymhosum Ag. Syst. Alg. p. 11. V. H. Syn. PL XVI f. 21. 



Marine: Japan (Grun.). 



The frustules live in hair-fine branched tubes. 



47. N. (Schizonema) mollis "W. Sm. (1856). — V. lanceolate, obtuse. L. 0,027 to 0,o32; 

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

 the middle, elsewhere parallel, finely lineate; lineolae forming longitudinal striae. — Schizon. mollr 

 W. Sm. B. D. n p. 77 PL LVHI f. 365. V. H. Syn. PL XV f. 22, 23. S. albicans V. H. Syn. 

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



Marine: Arctic Amercia, Cape Sabine! Bohuslan! 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. setaceum 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. 0,026; B. 0,oo5 

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

 interior of marine algae. — Cl. Diatomiste I p. 78 PL XII f. 12. 



Marine: South coast of Australia, in the thallus of a Chylocladia, sent by Prof . J. Agabdh! 



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

 L. 0,051 to 0,072; B. 0,01 to 0,008 mm. Axial and central areas indistinct. Striae 12 to 13 in 

 0,01 mm. parallel, finely lineate, lineolae forming longitudinal striae, about 30 in 0,oi mm. 



Forma caspia Grun. (1878). — L. 0,038 to 0,052; B. 0,oo7 to 0,oo8 mm. Striae 12 in 0,oi 

 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. 0. 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,oo7 to 0,oo8 mm. Striae 10 to 12 in 

 0,01 mm. — ScMzon. amplius V. H. Syn. PL XV f. 3. — A. S. N. S. D. Ill f. 5. 



Marine: North Sea! Canada! Mauritius! 



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

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

 As mentioned above, this species is nearly akin to N. mollis, and on the other hand- to smaller 

 forms of N. directa var. subtilis, from which iV. ramosissima can scarcely be distinguished. 



