ON THE FILLING UP OF RIVER-BEDS AND HARBOURS. 135 



3 1 . Navicula viridis. 



32. Synedra Ulna. 34. Thylacium semiorbiculare. 



33. Tabellaria trinodis. *35. Lithostylidium polyedrum. 



36. pupula. 



Of Icelandic marine Infusoria, procured from Algae, sent by Dr. Thie- 

 nemann, the following twelve species, still living, are found there, viz. : 



1. Cocconeis scutellum. 7. Navicula asper a. 



2. Denticella ? aurita. 8. gracilis ? 



3. Echinella ? Podosphenia ? 9. Podoslra moniliformis. 



4. Gomphonema clavatum. *10. Striatella Thienemanni. 

 5. minutissimum. 11. arcuata. 



*6. Grammatophora islandica. 12. Synedra fasciculata ? 



Among the fossil forms of the peat, are five new and peculiar ones, 

 and two among^the marine Infusoria. In the whole number of forty- 

 eight Icelandic Infusoria, there is no new genus ; but it is worth while 

 to remark the occurrence, together with the serrated Eunotise of Sweden, 

 Finland, and North America, which are characteristic of the North, 

 of Podosira moniliforms, which is elsewhere met with only in Peru. 

 V Equally interesting is the microscopic fauna of Labrador, which enu- 

 merates fifty-one living species, found in the earth, contained among the 

 roots of some mosses. The following forms are found near Okok in 

 Labrador : 



1. Amphora Ubyca. 17. Eunotia Faba. 

 *2. Arcella disphcera. 18. hexaodon. 



3. hyalina. 19. monodon. 



4. Cocconema asperum. 20. prterupta. 



5. gracile. 21. septena. 



*6. Lunula. 22. tetraodon. 



7. tenue. 23. triodon. 



8. Closlerium striolatum ? 24. Fragilaria binodis. 

 *9. Difflugia lagena. 25. Himantidium Arcus. 



10. oblong a ? 26. gracile. 



11. Eunotia amphioxys. 27. Navicula amphioxys. 



12. - biceps. 28. aspera. 



13. bidens. 29. ceratogramma. 



14. Camelus. 30. - ceratostigma. 



15. - - Diodon. 31. - crucigera. 



16. diadcma. 32. dicephala. 



