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92 Description of some New Species of Fossil Shells. 
tate to admit a possible error of ite than, y. independent of 
local attraction, and this cause mig) asily increase the error to 
a half degree. Ido not see how Prof. Locke can refuse his assent 
to this, after publishing the incinnati to be in Nov. 1837, 
70° 45.7, “a in April, 1840, writes, “I have lately found the dip 
at Cincinnati to vary between 70° 25’ and 70° 29’,” and yet in 
his last article he assigns 0/.86 as the imit of instrumental error. 
As for the errors of my own observations, given on page 87, I 
have twice observed the dip at Cleveland, on two opposite sides 
of the city, and in both instances have obtained a result greater 
than was to have been expected from its geographical position. 
The other three observations were in Michigan, where I was told 
P iron ore was quite abundant. 
Art. IX.—Description of some new species of Fossil Shells, from 
the Eocene, at Claiborne, Alabama; by Henry C. Lea. Phi- 
ladelphia, Oct. 17, 1840. 
Ir has long been a desideratum to the American geologist, to 
have the fossils of the widely extended beds of the tertiary forma- 
tion of this country, accurately described, and compared with 
those of a similar date in Europe. The works of my father, Mr. 
Conrad, and other geologists, have done much to effect this, but 
there are, still, no doubt, many undescribed species remaining. 
The following descriptions of species, which the author presumes 
io be new, are as exact as he was able to make them, as he fre- 
~ quently labored under the disadvantage of having but one speci- 
men of a shell, and that one often fractured. They were mostly 
obtained from a box of sand from the tertiary deposit at Claiborne, 
which my father has identified with the London clay, or caleaire 
grossiere of European geologists. The author hopes that his de- 
scriptions are sufficiently clear and minute to determine the spe- 
cles permanently. 
FAMILY MELANIANA. 
Genus Pasirura.—Lea. 
P. minima. PI. 1, fig. 1, 
P. testa subulata, imperforata, polita, tenuissima ; apice obtusa; 
suturis minimis; anfractibus » planulatis; columella levi; 
apertura ovata. 
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