LAND AND FRESH-WATER SHELLS 



NOETH AMEEICA. 



lY. 



PRELIMINARY OBSERVATION'S ON" THE 



Family STEEPOMATID^.* 



1. Classification. — Swainson, who may be consid- 

 ered the originator of the modern system of classifi- 

 cation of the families and genera of Mollusca (as 

 he was the first general conchologist who, breaking 

 through the trammels of Lamarckian nomenclature, 

 inaugurated the work since so boldly and successfully 

 continued l)y Dr. Gray and Messrs. H & A. Adams), 

 had, unfortunately, very little knowledge of the affin- 

 ities with the other Mollusca, of the so-called Mela- 

 nians inhabiting both America and the Old World, 

 since he has confounded them with marine shells 

 under his family Turhidce; but, notwithstanding 

 this error in the disposition of the whole group, he 

 had the sagacity to separate into numerous, and 

 generally well-characterized, genera, the incongru- 

 ous material which Lamarck had allowed to remain 

 under one generic name, — Melanla. 



Messrs. H. & A. Adams t approach more closely 

 to the present ideas of conchologists relating to this 

 subject, by separating from, but placing in close 

 neighljorhood to, the Cerithiadoi, their family Mela- 

 niidce, of which they admit two subfamilies, Melani- 



♦Ecprinted from the American Journal of Concliology, Vol. i, No. 

 2, 1805. 



t Genera of Recent Mollusca, i, 293. 



