Sketch of the Infusoria of the family Bacillaria. 105 



Fig. 9, 10. Actinocyclus. Fossil at Richmond, Va. 



Fig. 11. a, h. Actinocyclus. a, base ; 5, side view, showing the al- 

 ternate elevations and depressions which cause the light and dark por- 

 tions seen on a. Fossil at Richmond. 



Fig. 12. Coscinodiscus lineatus. Fossil in tertiary infusorial strata 

 of Virginia, at Richmond, and on Rappahannock River. 



Fig. 13. Coscinodiscus patina. With the preceding. 



Fig. 14. Coscinodiscus radiatus. With the preceding. 



Fig. 15. Scale representing yV^^jths of a millimetre, magnified 

 equally with the sketches. 



Fig. 16. a, &. Navicula viridis, recent and fossil, fluviatile, c, c, c, c, 

 the orifices. 



Fig. 17. a, h. Navicula viridis, copied from Ehrenberg. See page 97. 



Fig. 18. Navicula , marine, at Stonington, Conn. 



Fig. 19. Navicula , marine, with the preceding. 



Fig. 20. Navicula , fluviatile. West Point, &c. 



Fig. 21. a, 5. Navicula striatula, fluviatile, recent and fossil. 



Fig. 22. Navicula , fossil at Richmond, Va. 



Fig. 23. a, h. Navicula , fluviatile, recent and fossil. 



Fig. 24. a, h. Navicula sigma ? marine, Stonington. 



Fig. 25. a, h. Navicula , fossil at Richmond, Va. 



Fig. 26. a, b, c. Eunotia arcus, fluviatile, recent and fossil, c, cross 

 section. 



Fig. 27. a, &, c. Eunotia , brackish ditches, N. Jersey, c, cross 



section. 



g. 29. Eunotia diodon, 



g. 30. Eunotia triodon, , fl^^i^tile, recent and fossil. 

 31. Eunotia tetraodon, [ 



] 



Fig. 28. Eunotia monodon, ~ 



F " " " " 



F 



F 



F 



F 



F 



F 



F 



F 



F 



F 



F 



F 



F 



g. 32. Eunotia pentodon, 

 g. 33. Eunotia serra, 



g. 34. Cocconeis , marine, Florida. 



g. 35. Bacillaria paradoxa, marine, Hudson river. 



g. 36. a, b. Bacillaria tabellaris, ) fluviatile, recent 



g. 37. a, b. Bacillaria tabellaris, full grown } ) and fossil. 



g. 38. Bacillaria , marine, at Stonington, Conn. Recent. 



g. 39. Tessella catena ? marine, at Stonington, Conn. Recent. 



g.40. FragiUaria pectinalis, U^^iatile, recent and fossil, 

 g. 41. Jb ragularia Dipunctata .-^ ) 



g. 42. a, h. Meridion vernale, fluviatile, recent, and fossil in fragments. 

 Vol. XLii, No. 1.— Oct.-Dec. 1841. 14 



