ON THE FILLING UP OF RIVER-BEDS AND HARBOURS. 



137 



new ; consequently the number of species peculiar to America, amounts 

 to one hundred and two ; of those known as common to America and 

 the Islands, to two hundred and forty-five ; and of those known to be 

 yet living there to two hundred and ten. 



Besides this we are now able to determine the thirty-nine following 

 species from materials collected in the Sandwich Islands : 



1. Amphiprora navicularis. 



2. Cocconeis placentula. 



3. Cocconema fusidium. 



4. Difflugia hyalina. 



5. Eunotia amphioxys. 

 6. bicornis. 



7. Cocconema. 



8. gibba. 



9. pr (erupt a. 



10. Fragilaria striolata. 



*11. lamella. 



12. trachea. 



13. diopthalma. 



14. Gallionella distans. 



15. Gomphonema augur. 



16. clavatum. 



17 longiceps. 



18. rotundatum. 



22. Navicula curvula. 

 *23. distauridium. 



24. gibba. 



25. gracilis. 



*26. insularis. 



27. pusilla. 



28. sigma. 



29. viridis. 



30. Podosphenia cuneata ? 



31. Staurosira construens. 



32. Synedra scalaris. 

 *33. Tabellaria platysoma. 



34. rhabdosoma. 



35. Lithodontium bicorne. 



36. Lythostylidium rude. 



37. Spongilla acicularis. 



*38. Rotalia punctata. 



*39. Nodosaria punctata. 



19. Himantidium Arcus. 



20. Navicula amphisbtena. 

 21. cerate-stigma. 



Of these thirty-four belong to the silicious Infusoria ; three are si- 

 licious particles of plants ; and two are calcareous Polythalamia. From 

 the two latter forms the mass is distinctly indicated to be of marine 

 origin. Six species are peculiar ; all belong to known genera. 



Finally there is a small fauna of the Marian Islands, in which may 

 be reckoned thirteen species : 



1 . Cocconema fusidium . 



2. Fragilaria diopthalma. 



3. rhabdosoma. 



4. Gomphonema Augur. 



5. . clavatum. 



6. longiceps. 



7. Himantidium Arcus. 



8. Navicula pusilla. 



9. Navicula viridis. 



*10. Tetragramma libycum. 



1 1 . Spongia acicularis. 



*12. Amphidiscus. 



13. Rotalia globulosa. 



