126 
Prof. Ehrenberg on Microscopic Life 
the dust which fell on the ship on the high sea at that great 
distance from land. This dust has been universally regarded 
hitherto as volcanic ashes. The microscopic analysis has clearly 
shown that a considerable portion, perhaps one-sixth of the mass, 
consists of numerous species of Siliceous Polygastrica, and por¬ 
tions of silicated terrestrial plants, as follows :— 
A. SILICEOUS POLYGASTRICA. 
1. 
Campylodiscus Clypeus. 
10. 
Himantidium Arcus. 
2. 
Eunotia Aniphioxys. 
11. 
— Papilio. 
3. 
— gibberula. 
12. Navicula affinis ? 
4. 
Oalliontlla crenata. 
13. 
— lincolata. 
5. 
— distans. 
14. 
— Semen. 
6. 
— granulata. 
16. 
Pinnulariu borealis. 
7. 
— marcliica. 
16. 
— gibba. 
8. 
— procera. 
17. 
Surirella (peruviana ?) 
9. 
Gomphonema rotundatum 1 
18. Synedrn Ulna. 
B. SILICEOUS 
PHYTOLITHARIA. 
19. Amphidiscus Clavus. 
29. 
Lithostylidium Ossiculum. 
20. 
Lithodontium Bursa. 
30. 
— quadratum. 
21. 
— curvatum. 
31. 
— rude. 
22. 
— furcatum. 
32. 
— Serra. 
23. 
-— nasutum. 
33. 
— spiriferum. 
24. 
— truncatum. 
34. 
Spongolithis acicularis. 
26. 
Lithostylidium. Amphiodon. 
35. 
— aspera. 
26. 
— clavatuni, 
36. 
— mesogongyla. 
27. 
— cornutum. 
37. 
— obtusa. 
28. 
— Iteve. 
The forms included in this catalogue, mostly known and for 
the most part European, prove— 
1. That this meteoric shower of dust was of terrestrial origin. 
2. That it was not volcanic ash. 
3. That it was dust which had been lifted up to a great height 
from a dried-up marshy district by an unusually strong current of 
air or a whirlwind. 
