PLATE XXX. 



Figures magnified 500 diameters. 



Fig. 1. PLEUROSIGMA OBSCURTJM, W. S., S. B. D., I, p. 65, 20, f. 206, Sin. 



Sp. T., No. 407, Cleve., 1880, p. 49. " Probably 

 the same as P. peisonis, Gran., 1860, p. 562, 4, 

 f. 8," H. L. S. 

 " 2. " ATTENUATUM, W. S., S. B. D., I, p. 68, 22, f. 216, 



Sm. Sp. T., No. 395, V. H., 21, f. 11. 

 3. RIGIDUM, S. B. D., I, p. 64, 20, f. 198, Sm. Sp. T., 



No. 410, V. H., 19, f. 3. 

 4. NUBECULA, S. B. D., p. 64, 21, f. 201, Grun., 1860, 



p. 557. 



Fi-s. 5. (9). ANGULATUM, S. B. D., I, p. 65, 21, f. 205, A. M. 



H., 1852, p. 7, 1, f. 8, Sin. Sp. T., Nos. 389, 390. 



Figs. 6-8. " SPENCERII, W. S., S. B. D., I, p. 63, 22, f. 218. 



Figs. 10, 11. QUADRATUM, S. B. D., I. p. 65, 20, f. 204, Srn. Sp. 



T., No. 391. Only a var. of P. angulatuin. 

 Fig. 11, found in North America? H. L. S. 



Fig. 12. SCIOTENSE, Sullivant, Sill. J., 1859, (March), 



Prit., p. 917. Probably a var. of P. Spencerii 

 or attenuatum. 



" 13. Probably same as Collectonema eximium, Breb. 



" 14. " OBTUSATUM, Snllivarit, Sill. J., 1859, Prit., 919. 



Figs. 15, 16. MASTOGLOIA EXIGUA, Lewis, N. R. Sp., p. 7, 2, f. 5, V. H., 4, f. 



25, 26, Sm. Sp. T., No. 676. Lewis, letters and 

 also annotated copy of his paper describe this 

 diatom as only a variety (immature) of Mast, 

 lanceolata, H. L. S. 

 " 17, is. GREVILLEI, W. S., S. B. D., II, 65, 62, f. 389, M. 



J., 1856, 1, f. 16, V. H., 4, f. 20. 

 Fig. 19. LANCEOLATA, S. B. D., II, p. 64, 54, f. 340, Sm. 



Sp. T., No. 214, V. H., 4, f. 15 and 17. 

 20-23. SMITHII, Thw., S. B. D., II, 65, 54, f. 341, Grun., 



1860, p. 57, 5, 5, f. 11, V. H., 4, f. 13. 



24, 25. CERATONEIS ARCUS, Kg., K. B., f. 104, 6, f. 10, Rab., S. D., p. 37, 



7, f. 3, Sm. Sp. T., 9, No. 66, V. H,, 37, f. 7. 



