GEOLOGY—INFUSORIA. 
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Basaltic(P) rock; Mud Creek canon, Sierra Nevada. 
Foliating trapp-porphyry; Mud Creek canon, Sierra Nevada. 
Granitic trachyte; west of Black butte. 
Lava; near Black butte, Sierra Nevada. 
Trachyte; upper waters of Sacramento or Pitt river. 
Black silicious rock; near Humboldt river. 
Porpbyritic trachyte; Sacramento or Pitt river. 
Argillaceous porphyry; Sevier river, 1853. 
Granitic porphyry; Granite mountain, Desert near Great Salt lake. 
Granite; Humboldt mountains. 
Black shale; Sacramento or Pitt river. 
Gold-bearing quartz; California; presented by Captain Miller, Quartermaster, 
United States Army. 
Petrified oak block; Cow creek, California; presented by Captain M. S. Miller, 
Quartermaster, United States Army. 
II.— Letter from Professor J. W. Bailey upon Infusorial Fossils submitted to him by Dr. Schiel. 
West Point, N. Y., December 14, 1854. 
Dear Sir: I have been requested by Dr. Schiel to send to you some drawings of the fossil 
Diatoms found by him in California. As I have a considerable amount of matter on hand which 
claims precedence to this, I have only had time to make the accompanying notes and sketches, 
which can he disposed of as you may think best. 
Specimen No. 1 .—Honey Lake Valley. 
This is a fine, grayish white powder, chiefly composed of Diatomaceous shells, all of which 
are of fresh-water origin, and probably of recent date. The following are the chief species 
which I have noticed :• 
Epithemia, allied to E. Westermanni; several varieties of form, perhaps several species. 
See Figs. 5, 6. 
Cocconema asperum, Ehr. 
Cocconema cymhiforme, Ehr. 
Discoplea atmosphaerica, Ehr. 
Surirella campylodiscus, (?) Ehr. Fig. 4, a, b. 
Cocceneis. Fig. 3. 
Cymbella gibba, Bailey. Fig. 1. 
Cymatopleura (?) Campylodiscus, Bailey. Fig. 2, a, b. 
The last two species I believe to he new, and they may he characterized as follows : 
1. Cymbella gibba. —Bailey, (Fig. 1.) Bases somewhat triangular, rounded, and very gib¬ 
bous on the dorsal side, slightly concave on the ventral side. Length, of an inch ; width, 
about two-thirds of the length. Locality, Honey Lake valley. 
2. Cymatopleura (?) Campylodiscus. —Bailey, (Fig. 2, a, b.) Bases circular, or sometimes 
irregularly bent like a Campylodiscus, marked with one deep transverse undulation. Margins 
strongly striated. Diameter, T0 4 00 - to TTJ 5 ^ of an inch. Locality, Honey Lake valley. 
Specimen No. 2.— Junction of Canoe creek and Sacramento river, California. 
A fine, white powder, chiefly composed of a minute species of Galleinella. (See Fig. .) 
It is undoubtedly of fresh-water origin, hut contains some circular discs so much resembling 
the marine Actinocycli, that a mistake as to its origin might easily he made. By careful ex- 
