22 



another kind of these curious domicils in Wissa- 

 liickon creek, so perfectly hke a Crepidula, that it 

 might with equal propriety be added to the specie? 

 of that genus. Should Mr. Lea obtain this, he may 

 erect a new genus to receive it; as fresh water and 

 marine shells, according to his theory, cannot with 

 propriety be arranged in the same genus. The shell- 

 formed receptacle of the Phryganea, called by this 

 writer Valvata arenifera, is widely distributed 

 throughout the United States. It abounds near Plii- 

 ladelphia and in the vicinity of Baltimore, and I have 

 found it equally abundant in a creek in South Ala- 

 bama. I never mistook it for a shell, not even wlien 

 I collected it, during my solitary rambles in early 

 youth, along the wild and romantic banks of the 

 Wissahickon, where a passion for the beautiful in 

 nature, as w^ell as a taste for natural science, often 

 led me on the fine days of autumn and si)ring. 



It is with pleasure I acknowledge the assistance I 

 have received in prosecuting my researches, from the 

 kindness and liberality of several gentlemen in Ala- 

 bama. I shall ever feel grateful to them for their 

 attentions to a stranger, who sought health in the 

 bland air of a southern clime, and recreation and in- 

 struction in the study of fossiiiferous strata, in a 

 State, probably the richest of the Union in organic 

 remains, and certainly more interesting than any 



