178 Prof. Ehrenberg on Microscopic Life 



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



neii-o 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. Galliondla sulcata. 8. — peregrina. 



4. Haliomma radiatum. 9. Surirella sigmoidea. 



5. Navicula dirhynchus. 10. Synedra Ulna. 



B. SILICEOUS PHYTOLITHARIA. 



IL Spongolithis aapeva. 13. Spongolifhi^ Fustis. 



12. — ceuocephala. 14. — vayinata. 



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



in Brazil, in 0° lat., 28° W. long. 



A. SILICEOUS POLYGASTRICA. 



1. F?'fl</i7arta rhabdosoma. 2. Fragilaria '^a.s'xcuXa.. 



B. SILICEOUS PHYTOLITHARIA. 



3. Lithostglidiian 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 Pini. 



It follows from these fom- series of observations obtained 

 through ]\I. Scliayer, that the ocean, in its usual condition, 

 without peculiarity of colour, ^^ithout storms and other in- 

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

 perfect and wholly invisible organisms suspended in it, and that 

 the sihceous-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., 26° W. 

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



Mr. Darv\du, the well-known and most meritorious English 

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

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



