PLATE XLII. 



Figures magnified 500 diameters. 



Fig. 1. NITZSCHIA VALIDA, forma loiigissima, Cleve. and Grun., 1878, 



p. 12, 3, f. 19; J. M:, 1879, p. 33, 2, f. 19; V. H., 65, 

 f. 4, 5. 



Figs. 2, 3. parts of same seen under high power, about 'T- -. 



Fig. 4. MAJOR, Gruu., V. H., 65, f. 6, (N. Sigma var.). 



5. parts of same under higher power. 



Figs. 6, 8. BREBISSONII, S. B. D., 31, f. 266; V. H., 64, f. 4, 5. 



Figs, should be beaded along the edge. 



Fig. 7. OBTTJSA, smaller form, compare Fig. 18. 



" 9. SIGMOIDEA, S. B. P., 13, f. 104; Prit., 781, 7, f. 148; 



V. H., 63, f. 5-7. 

 Figs. 10, 11. SIGMA, S. B. D., 13, f. 108; Prit., 781, 4, f. 21 ; V. H., 



65, f. 7, 8; Sm. Sp. T., No. 367. 

 12-15. VERMiouLARis, Hantz., Prit., 781 ; V. H., 64, f. 1, 2. 



All are small forms of sigmoidea. 

 16, (21). VITREA, Norm., T. M. S., 1861, p. 7, 2, f. 4 ; V. H. r 67, 



f. 10; Sm. Sp. T., No. 376. 



Fig. 17. LINEARIS, S. B. D., 13, f. 110 and 31, f. 110; V. H.,(>7, 



f. 13-15 ; Sm. Sp. T., Nos. 353, 354. Striae fine and 

 light. Fig. too heavy. 

 18. OBTUSA, S. B. D., 13, f. 109; V. H., 67, f. 1 ; Sm. Sp. 



T., No. 358. Vide Fig. 7. 

 Figs. 19, 20. DISSIPATA, Rab. Alg. Sachv., No. 948; V. H., 63, f. 



1-3. 



Fig. 21. VITREA, Norm., forma major. Vide Fig. 16. 



" 22. LINEARIS, Vide Fig. 17. 



" 23. VITREA, Normal form. Vide Figs. 16, 21. 



