p. 30

-30-
1828.

specimens which I collected during the past season at the Rapids of the Ohio river: they are nearly all numbered, and I have duplicates marked with the same number. I can refer to the same in my collection. I have given the names of such of the 33 specimens as I know: they may not however be correct in every case. I have left a blank opposite such as I can not ascertain, which I would thank you to fill up and transmit to me their names.*** The river being high at present, I can procure no more containing petroleum. I send you however a vial containing petroleum that was collected last summer. The petroleum occurs in the lime rock from which the specimens 1 to 5 were taken as you will perceive by their peculiar smell.

I have also collected a few shells from the Ohio river, at this place, which will serve to show the conchology.***
Should they prove interesting to you, I should be much gratified to have their names. Nos. 1,2, & 3 are all the univalves which I have collected, and I believe are all that inhabit the river at this place. No. 10 Unio purpurens: No. 11 U. crassus[;12] 12, I can not ascertain: No. 14 U. ovatus: No. 15 is probably a young shell. The three small bivalves are not numbered because I have no duplicate.***

You will observe that I have given names to some of the shells, but still I am not certain that they are correct. I have descriptions of nearly all the land and fresh-water shells of the U.S., but I can not determine all the names, until I have become more familiar with the terms which are employed. In return I would be thankful for the nine minerals which constitute the geological alphabet (excepting limestone), and such others, should you think mine of more value, as you would recommend to a