9 



occurs there. How many more of the western spe- 

 cies inhabit the Atlantic rivers of East Florida, is an 

 interesting problem which some future observer 

 must solve. 



The propriety of separating the Naiades into so 

 great a number of species, especially as they have 

 been divided by RAFiNEsauE and Lea, has often been 

 doubted by conchologists. In general, however, 

 they are sufficiently defined, although Mr. Lea has 

 imposed nev/ names of his own upon species long 

 before described by others, evidently wishing to be 

 considered sole authority in this branch of Concholo- 

 gy. Few, however, vv^ill be willing to take his ipse 

 dixit for the justice of his claims. 



Colour of the nacre. This has been supposed to 

 be characteristic of certain species, which, it is said, 

 never vary materially in the colour of the interior. 

 Thus, U7iio ater, Lea, U. torsus, Raf. and some 

 others are invariably purple or rose coloured; but in 

 others again, the nacre varies from pure white to 

 every shade of salmon, rose colour, pink and purple. 

 The '^Unio nasutits, of Say, is a good example of 



* Mr. Lea observes that the U. nasutusls "either white 

 or approaching salmon colour under the bealcs." I, many 



