NATURAL HISTORY OF THE DIATOMACEJE. 50I 



Fig. 15. Front view of a chain of two frustules of Grammatophora marina, from the 



harbor of Salem, Mass. 

 Fig. 16. Front view of a filament of Mclosira varians, terminated by a sporangium or 



seed vessel. From Englewood, N. J. 

 Fig. 17. Side view of Heliopelta Metii, from the marine fossil stratum of Nottingham, 



Md. The species has been lately removed from the genus Heliopelta and placed 



in Actinopty chits, and can therefore be considered as a representative of that 



genus. It is one of the most beautiful of the diatoms, and has never as yet been 



seen except in the fossil condition, and at the locality named. 

 Fig. 18. End and portion of a tube of Schisonetna obtusitin, from the harbor of New 



York. The little navicula-like frustules of the ScJiizone»ia are seen within the 



tube. 

 Fig. 19. A group showing both front and side view of Synedra tabulata, from the 



harbor of New York, showing the manner in which the frustules are attached to 



submerged objects by means of a cushion or short stipes. 

 Fig. 20. A chain of Diatoma vulgare, from England, showing the front view only. 

 Fig. 21. Side view of BidditlpJiia rhombus. From the harbor of Charleston, S. C. 

 Fig. 22. Front view of Biddulphia rJiombus, showing both valves and connecting 



membrane. From the harbor of Charleston, S. C. 



Plate III. 



Fig. 23. A, B, C, D, and E, different stages of growth of Pahiwgkca. 



Fig. 24. Lichmophora flabellata on its stipes or stalk. From the coast of England. 



Fig. 25. Side view of Navicula Barklayana. From the coast of England. 



Fig. 26. EpitJicviia turgida, conjugating or reproducing. From England. 



Fig. 27. Side view of Pinnularia lata. From New Hampshire. 



Fig. 28. Side view of Aulacodiscus Orcgonctisis. From the Sandwich islands. 



Fig. 29. Side view of a Navicula pratexta. From the Gulf of Mexico. 



Fig. 30. Side view of Himantidium pectinale. 



Fig. 31. Front view of a filament of Himantidiuni pectinalc, from a spring near New 



York. 

 Fig. 32. Side view of Meridian circularc, showing the wedge-shaped frustules united 



together so as to form a spiral. From West Point, N. Y. 

 Fig. 33. Side view of Stauroneis acuta. 

 Fig. 34. Front view of Stauroneis acuta. From England. In these two figures the 



septum, which projects like a shelf into the cavity of the frustule at the ends, can 



be seen. 

 Fig. 35. Side view of Navicula lyra. From Germany. 

 Fig. 36. Side view of Navicula serians. From New Hampshire. 

 Fig. 37. Side view of Navicula quadrata. From Germany. 



