A Manual of Conchology / According to the System Laid Down by Lamarck, with the Late Improvements by De Blainville. Exemplified and Arranged for the Use of Students.

by Thomas Wyatt

2. Cyrena. Ten species.

This genus of shells is found in rapid rivers and streams; it was formerly classed with the Cyclas, from which, however, it greatly differs in having three cardinal teeth on each valve, and also lateral teeth. They are thick, solid shells, sometimes of a large size; the apices always eroded or carious.

Shell rounded and trigonal, ventricose, inequilateral; hinge with three teeth on each valve; two lateral teeth, one of which is near the primary ones; ligament exterior, placed on the largest side; in some species the lateral teeth are crenulated, in others they are entire.

Cyrena trigonella.

C. orientalis.

C. cor.

C. depressa.

C. Caroliniensis.

C. fuscata.

C. fluminea.