92 Description of some New Species of Fossil Shells. 



tate to admit a possible error of more than 10' independent of 

 local attraction, and this cause might easily increase the error to 

 a half degree. I do not see how Prof. Locke can refuse his assent 

 to this, after publishing the dip at Cincinnati to be in Nov. 1837, 

 70° 45'.7, and 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 limit 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 

 iron ore was quite abundant. 



Art. IX. — -Description of some new species of Fossil Shells, from, 

 the Eocene, at Claibor7ie, Alabama ; by Henry C. Lea. Phi- 

 ladelphia, Oct. 17, 1840. 



It 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 eflect this, but 

 there are, still, no doubt, many undescribed species remaining. 

 The following descriptions of species, which the author presumes 

 to 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 calcaire 

 grossiere of European geologists. The author hopes that his de- 

 scriptions are sufficiently clear and minute to determine the spe- 

 cies permanently. 



FAMILY MELANIANA. 



Genus Pasithea. — Lea. 



P. minima. PI. 1, fig. 1. 



P. testa subulata, imperforata, polita, tenuissima ; apice obtusa ; 



suturis minimis ; anfractibus , planulatis ; columella la3vi ; 



apertura ovata. 



