32 THE NAUTILUS. 



and not " dark green " as Lea describes it. May not the green tint 

 have been due to conferva? ? Accompanying the specimens of ' obtiisn. 

 Whit./ is a ticket ' emarginata Say,' in Frauenfeld's own hand- 

 writing. I do not see how they can be separated from the form de- 

 scribed and figured by Kiister as ' emarginata ' of Say, or in other 

 words, I consider them the same species." 



This would certainly seem to be conclusive as to the identity of 

 Krister's "emarginata" with Lea's " obtusa." And, as for the 

 reason above given, Lea's name cannot be used, it follows that the 

 species must hereafter be known as " emarginata Kiister." As to 

 the proper generic designation, the investigation of the radula by 

 Messrs. Pilsbry and Beecher shows the species to belong to the 

 genus Gincinnatia, the dentition being like that of " Amnicola " 

 cincinnatiensis Anth., and unlike all other known species of " Bythi- 

 nella" or Amnicola. 



The complete synonymy of our species will then stand as fol- 

 lows : 



ClNCINNATIA EMARGINATA (KlJfiT.). 



1841. Paludina obtusa Lea, Proc. Am. Phil. Soc. II., p. 34, non 



Troschel (1837), Wiegm., Archiv, I., p. 173. 



1844. Paludina obtusa Lea, Trans. Am. Phil. Soc. IX., p. 13. 



1848. Paludina obtusa Lea, Obs. Gen. Unio, IV., p. 13. 



1844. Amnicola obtusa Lea, Hald. Mon. F. W. Univ. Moll., p. 24. 



1862. Amnicola obtusa Binney Desc. Cat. Amnicola, &c, p. 10. 

 1865. Bythinella obtusa Stimp., Hydrobiinae, p. 20. 



1865. Bythinella obtusa Binney, L. & F. W. Shells, N. A. III., 

 p. 69, fig. 138. 



1870. Bythinella obtusa Tryon, Mon. F. W. Univ. Moll., p. 48, pi. 

 16, fig. 6. 



1852. Paludina emarginata Krist., Paludina, Conch. Cab., p. 50, 

 pi. 10, rigs. 3 A: 4. 



1863. Amnicola emarginata, Frrid., Verb. Zool.-bot. Ges. Wien. 

 XIII. , p. 1030. 



1865. Amnicola cincinnatiensis Binney L. & F. W. Shells, N. A., 

 p. 85, fig. 169. 



