10 LIMNEA EMARGINATA. 



subgenus Radix; on which account, a more characteristic 

 species should have been given as the example (as L. 

 jugularis;) but there might be some risk in citing an ani- 

 mal which I never saw, and which might possibly possess 

 anomalous characters. Thus the editors of the current 

 edition of the Regne Animal, instead of following their 

 rule of figuring none but the best known species, have de- 

 parted from it in preferring 'Cistuda clausa' (C. Carolina) 

 a land animal, instead of figuring Terrapene Europsea, in 

 illustration of the text: "On doit remarquer parmi les 

 tortues d'eau douce, les tortues a boite." A little caution, 

 in the study of the Mollusca, cannot be misplaced; when 

 authors like Cuvier and Duvernoy have confounded the 

 Testudininae with the Emydae, by placing too much con- 

 fidence in the character of the shells. 



LIMNEA EMARGINATA, Say. 



PLATE 2. 



L. testa tenui, subdiaphana, anfractibus quaternis vel 

 quinis convexis, ultimo maximo: sutura valde impressa: 

 apice acuto: crena columellari profunde emarginata. 



SYNONYMS AND REFERENCES. 



LIMNEUS EMARGINATUS, SAY. Journ. Acad. Nat. Sci., 

 vol. ii. p. 270. American Conchology, pi. 55, fig. 1. 



