PLATE XXVIII. 



Figure 1. Pleurosigma elegantissimum, n. sp. 



2. Pleurosigma speciosum, W. Sm., var. nov. 

 ,, 3. Pleurosigma naviculaceum, Breb., var. nov. 

 ,, 4. Pleurosigma thaitiense, n. sp. . 

 „ 5. Pleurosigma arafurense, u sp. 



6. Pleurosigma smithianum, n. sp. 

 „ 7. Navicula bullata, Norman, var. carinata, nov, 

 ,, 8. Navicula zanzibarica, Grev., var. zebuana, nov 

 ,, 9. Navicula spectabilis, Grev., var. nov. . 

 „ 10. Navicula bullata, Norman, var. obtusa, nov. 

 „ 11. Navicula (V) jejuna, A. S., var. nov. . 

 „ 12. Navicula parallela, n. sp. 

 „ 13. Navicula, sp. (?) 



„ 14. Alloioneis antillarum, CI. et Grun., var. nov 

 ,, 15. Navicula, sp. 

 ,, 16. Navicula kerguelenensis, n. sp. 

 ,, 17. Navicula, sp. (?) 

 „ 18. Navicula cyclophora, n. sp. 

 ,, 19. Navicula abnor mis (?), n. sp. . 



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