178 Prof. Ehrenberg on Microscopic Life 



2. Water from the region of the Brazilian coast near Rio de Ja- 



neiro on the high sea, in 23° S. lat., 28° W. long. 



A. SILICEOUS POLYGASTRICA. 



1. Coccone'is Scutellum. 6. Navicula Scalprum. 



2. Fragilaria Navicula. 7, Pinnularia oceanica. 



3. Gallionella sulcata. 8. — peregrina. 



4. Haliomma radiatum. 9. Surirella sigmoidea. 



5. Navicula dirhynchus. 10. Synedra Ulna. 



B. SILICEOUS PHYTOLITHARIA. 



11. Spongolithis aspera. 13. Spong olithis Fustis. 



12. — cenocephala. 14. — vaginata. 



3. Water from the equatorial ocean in the direction of St, Louis 



in Brazil, in 0° lat., 28° W. long. 



A, SILICEOUS POLYGASTRICA. 



1. Fragilaria rhabdosoma. 2. Fragilaria Navicula. 



B. SILICEOUS PHYTOLITHARIA. 



3. Lithostylidium rude. 4. Lithostylidium Serra. 



4. Water from the Antilles Ocean, 24° N. lat., 40° W. long. 



A. SILICEOUS POLYGASTRICA. 

 1. Haliomma radiatum. 



B. SILICEOUS PHYTOLITHARIA. 



2. Lithodontium nasutura. 4. Lithostylidium rude. 



3. Lithostylidium Amphiodon. 



C. MEMBRANOUS PORTIONS OF PLANTS. 

 5. Pollen Vml 



It follows from these four series of observations obtained 

 through M. Schayer, that the ocean, in its usual condition, 

 without peculiarity of colour, without storms and other in- 

 fluences, contains, in the most transparent sea-water, numerous 

 perfect and wholly invisible organisms suspended in it, and that 

 the siliceous-shelled species are the most predominant in all those 

 cases, although the analysis of sea-water does not show silica as 

 a constant ingredient. 



III. On a Cloud of Dust which rendered the whole air hazy for a 

 long time on the high Atlantic Ocean in 17°43'iV. lat. y 26° W. 

 long., and its being constituted of numerous siliceous animalcules. 



Mr. Darwin, the well-known and most meritorious English 

 traveller and writer on coral reefs, relates in the account of his 

 travels, that a fine dust constantly fell from the hazy atmo- 



