300 



MELANIIN^. 



Si/n. Melafusus, Swains. Glotella, Gray. 



Ex. I. fluviatilis, Say, pi. 31, fig. 8. Operculum, I. 

 fluviatilis, fig. 8, a, 8, h. 



The species of lo inhabit the rivers of North America ; 

 the shells, like those of most of the MelanUdie, are 

 covered with a brown, black, or olivaceous epidermis, and 

 are remarkable for the peculiar elongation of the axis 

 anteriorly, and for the spinose nature of the last whorl. 



Species oj lo. 



armigera, Lert. 

 Duttoniana, Lea. 

 Florentiaua, Lica. 

 fluviatilis, Say. 

 fusiformis, Say. 

 nobilis, Lea. 

 pagodula, Gould 



pernodosa, Lea. 

 plicata, Lea. 

 robuliua, Antlwn. 

 spinigera, Lea. 

 spinosa, Lea. 

 tenebrosa, Lea. 

 tuberculata, Lea. 



Sub-gen. elimia, H. and A. Adams. 



Shell fusiformlj ovate ; whorls reticulate or nodulose, carinate 

 in the middle; aperture greatly produced anteriorly; outer lip 

 thin, simple, acute. 



acuticarinata, Lea. 

 apis. Lea. 

 bella, Co7ir. 

 Boykiniana, Lea. 

 caliginosa. Lea. 

 caucellata, Say. 

 carinocostata, Lea. 

 catenaria, Say. 



catenoides, Lea. 

 elevata, Lea. 

 filum, Lea. 

 Holstonia, Lea. 

 nodulosa, Lea. 

 Potosieusis, Lea. 

 spinalis, Lea. 

 torta, Lea. 



