374 On Infusoria in Dust-showers and Blood-rain. 
IV. Sirocco dust, of Genoa, May 16, 1846.—In this dust, Eh- 
renberg found 22 species of Polygastrica, 21 of Phytolitharia, and 
3 of parts of plants. he forms have much resemblance to those 
of the Malta and Atlantic showers. The color is yellowish or 
dust, and about {th to td of the mass is organic. None of the 
species are characteristic African forms, and Synedra enlomon is 
South American. This dust was analyzed by Dr. Wolcott 
Gibbs, who obtained for its composition, excluding the water and 
organic matter which amounted to 18:5: 
yo Bie TH Fe Mn €a0 = Mg K Na Ca 
45575 20347 9388 4222 11648 2209 38645 2332 0:306=100. 
The carbonate of lime is from Polvthalamia. 
It follows from the preceding results that the showers of the 
Atlantic, of Malta and of Genoa are in general alike in orgamic as 
well as inorganic constitution, and in the absence of characterts- 
tic African forms ; and this resemblance is the more surprising as 
the observations extend through the long period of 16 years, from 
1830, to 1846, They are alike also in the brownish-red color of 
the dust. 
V. Sirocco dust of Lyons, Oct. 17, 1846.—The Lyons shower 
afforded 39 species of Polygastrica, 25 of Phytolitharia, 3 of Po- 
lythalamia besides minute portions of plants. The accompany- 
ing plate from Plate 5, of Ehrenberg’s work, contains 104 out of 
123 of his figures, the species of Polythalamia, Spongolithis, and 
portions of plants being omitted. ‘The species here figured are 
as follows :* eas 
1. Polygastrica. 
1, 2, Gallionella granulata. 88 Eunotia tridentula. 
3 ecussata, 39 Eunotia? levis. 
4 —— procera. 40 Himantidium Arcus. 
5,6, 7 —— istans. 41,42, Tabellaria. 
8,9, Discoplea atmospherica. 43 Fragilaria pinnata? 
LO, Coscinodiscus ? 44 Cocconeis lineata. : 
11, Trachelomonas levis. atmospherica. 
12, Campylodiscus clypeus. 46 Navicula Bacillum. 
13, 14, 15, Gomphonema gracile. ——  amphioxys. 
16, 17, Cocconema cornutum (nec gracile.)| 48,49 —— Semen. 
; 0 —— © lineolata? 
' 19, 20, Eunotia longicornis. 51 Pinnularia borealis. 
21,22 —— longicornis. |62  ——  viridula. 
23 —— Argus. 53 ——_—SséViridis. 
2. -— longicornis. 54 —_ teniata (n. sp.) 
25 —— granulata? 55 ualis ? 
26 —— zebrina? (Argus ?) 56 Surirella Craticula ? 
27. *...—— Monodon? 57, 58, Synedra ulna. 
28-32 —— amphioxys(31,cwmovario)., 59, 60, Fragilaria pinnata? 
83,34 —— gibberula. 61 Grammatophora ? | 
788 —— zebrina? 62, 63, Incerti generis (1). 
36 Himantidium zygodon? 64 Incerti generis (2). — © 
fi Ennotia gibbe. ; _| 65 Incerti generis (3) (4 
oe 
