eaten CONCHOLOGY. 69 
teeth, the cardinal divided into numerous radiations, anterior ones 
smaller, the others lamellar and long. Inhabits the lakes and 
rivers of America. ‘Two species. 
\ Atyria avicularis.* Hyria corrugata.* 
Notre.—Alasmidonta. Separated by Say from the Anodonta by its pri- 
mary tooth, and from the Unio by being destitute of the lamelliform teeth. 
Shell. Transverse, equivalve, inequilateral ; hinge with a primary tooth 
in each valve; cicatrices three. Four species. 
A. undulata. A. marginata. 
A. ambigua. A. confragosa. 
3. Genus Anodonta. Pl. 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. Anodonta anatina. 
A. marginata. A. sinuosa, 
A. rubens. A. Patagonica. 
A. anatina. A. cygnea. 
A. fragilis. A. sulcata. 
A. trapezialis. A. cataracta. 
A. rufa. A. exotica 
A. uniopsis. A. crispata. 
A. intermedia. A. Pennsylvanica. 
A. glauca. A. maximus. 
The following species are American. 
Anodonta magnifica. Lea. Anodonta gigantea. Lea. 
A. Woodiana 4 A. incerta. is 
A. angulata. 3 A. Pepiniana. FP 
A. Benedictensis. a A. plana. Es 
A. cylindracea fe A. salmonia. “4 
A. decora. ss A. Stewartiana. 5 
A. edentula e A. subcylindracea. __,, 
