154 APPENDIX. 



6. Lymneus reflexus, Say. 1. c. pi. xxxi. fig. 2. Rainy Lake, 

 Seine River, and Lake Winnipec. 



7. Lymneus stagnalis. Lake a la Crosse, Upper Mississippi. 



PALUDINA. 



8. Paltjdina ponderosa, Say. Wisconsin River. 



9. Paludina vivipara, Say. Am. Con. i. pi. x. The American 

 specimens of this shell are more depressed than the European, but ap- 

 pear to be identical in species. 



MELANIA. 



10. Melania virginica, Say. Lake Michigan. 



ANODONTA. 



11. Anodonta cataracta, Say. Chicago, Lake Michigan. Tliis 

 species, Mr. Lea remarks, has a great geographical extension. 



12. Anodonta corpulenta, Nobis. Shell thin and fragile, though 

 less so than others of the genus ; much inflated at the umbones, margins 

 somewhat compressed ; valves connate over the hinge in perfect speci- 

 mens ; surface dark brown, in old shells ; in younger, of a pale dingy 

 green, and without rays, in all I have examined ; beaks slightly undula- 

 ted at tip. The color within is generally of a livid coppery hue, but 

 sometimes, also, pure white. 



Length of a middling sized specimen, four and a half inches, breadth, 

 six and a quarter. It is often eighteeen inches in circumference, round 

 the border of the valves, with a diameter through the umbones of three 

 inches. Inhabits the Upper Mississippi, from Prairie du Chien to Lake 

 Pepin. 



This fine shell, much the largest I have seen of the genus, was first sent 

 by Mr. Schoolcraft, to the Lyceum, several years ago. So far as I am 

 able to discover, it is undescribed, and a distinct and remarkable species. 

 It may be known by its length being greater in proportion to its breadth 

 than in the other American species, by the subrhomboidal form of the pos- 

 terior half, and, generally, by the color of the nacre, though this is not to 

 be relied on. It appears to belong to the genus Symphynota of Mr. Lea. 



ALASMODONTA. 



13. Alasmodonta complanata, Barnes. Symphynota co3ipla- 

 nata, Lea. Shell Lake, River St. Croix, Upper Mississippi. Many 

 species of shells tound in this lake grow to en extraordinary size. Some 

 of the present .collected by Mr. Schoolcraft, measure nineteen inches in 

 circumference. 



14. Alasmadonta rugosa. Barnes. St. Croix River, and Lake 

 Vaseux, St. Mary's River. 



