CONCHOLOGY. 59 



teeth, the cardinal divided into numerous radiations, anterior ones 

 smaller, the others lamellar and long. Inhabits the lakes and 

 rivers of America. Two species. 



Hyria avicularis.* Hyria corrugata.* 



Note. — ilasmidonta. Separated by Say from the Anoilonta by its pri- 

 mary tooth, and from thcUnio by being destitute of the lamelliform teeth. 

 Shell. Transverse, equi valve, inequilateral ; hinge with a primary tooth 

 in each valve ; cicatrices three. Four species. 



A. undulata. A. marginata. 



A. aiiibigua. A. confragosa. 



3. Genus Anodonta. PI. VIII. 



Animal. As above. 



Shell. Rather thin, regular, close, equivalve, inequilateral ; 

 summit anterodorsal ; hinge entirely without teeth, with a post- 

 apicial lamina ; ligament external, dorsal, and postapicial, two well 

 marked muscular impressions, besides those of the retractile 

 muscles. Inhabits fresh-water lakes in Europe and America. 

 Forty-nine living species ; and many fossil. 



Anodonta areolatus. 

 A. marginata. 

 A. rubens. 

 A. anatina. 

 A. fragilis. 

 A. trapeziaUs. 

 A. rufa. 

 A. uniopsis. 

 A. intermedia. 

 A. slauca. 



Anodonta anatina. 



A. sinuosa. 



A. Patagonica. 



A. cygnsea. 



A. sulcata. 



A. cataracta. 



A. exotica 



A. crispata. 



A. Pennsylvanica. 



A. maximus. 



The following species are American. 



Anodonta magnifica. Lea. 

 A. Woodiana „ 



A. angulata. „ 



A. Benedictensis. „ 



A. cylindracea ,, 



A. decora. ,, 



A. edentula 



Anodonta gigantea. Lea. 



A. incerta. 



A. Pepiniana. 



A. plana. 



A. salmonia. 



A. Stewartiana. 



AT subcvlindracea. 



