NORTH AMERICAN CONCHOLOGY. 33 



[Chenu, Bibliotheque Conchyliologique.] 



SnB-FAMiLY Alasiuidia. 



Genus ALASMIDONTA. 



26 Alasmidonta marginata Say. 



27 iii 15, 16 costata Raf. 



Scb-Familt Cyc9adia. 



Genus CYCLAS. 

 Sub-Genus Polymesoda. 

 27 Cyclas Caroliniana Bosc. 



Sub-Genus Phymepoda. 



27 Cyclas lacustris Ruf. 



27 dubia Say. 



Sub-Genus Amesoda. 



27 Cyclas similis Say. 



27 lasmampsis Raf. 



Sub-Genus Cokbicula Megerle. 



27 Cyclas hamalis Ruf. 



27 fluviatilis R<f. 



27 iii 19-21 lasmampsis Raf. 



Aiiicroda lasmajnpsis Raf. 



28 equalis Raf. 



Pliymesoda equalis Raf. 



Genus TREMESIA. 



29 iii 22-24 Tremesia patelloides Raf. 



Nolrema patelloides Raf. 

 29 Mytilus recurvus Raf 



29 Unio (Elliptio) teres Raf 



30 (Obliquaria) sinuata Raf 



30 atroviolacea Raf. 



30 Cliffordiana Raf 



30 Amblema antrosa Raf 



Obocaria puchostea Raf. 



