32 THE NAUTILUS. 



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

 have been due to confervas ? Accompanying the specimens of ' obtusa 

 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 

 Kiister'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 Ku'ster." As to 

 the proper generic designation, the investigation of the radula by 

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

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

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

 nelfa" or Amnicola. 



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

 lows : 



ClNCINNATIA EMARGINATA (KUST.). 



1841. Pahidina obtusa Lea, Proc. Am. Phil. Soc. II., p. 34, won 

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



1844. Pahidina oblusa Lea, Trans. Am. Phil. Soc. IX., p. 13. 



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



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



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

 1865. Byihinella obtusa Stimp., Hydrobiina?, p. 20. 



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

 p. 69, fig. 138. 



1870. Bylhinella oblusa Tryon, Mon. F. W. Univ. Moll., p. 48, pi. 

 16, fig. 6. 



1852. Pahidina emarginata Kiist., Paludina, Conch. Cab., p. 50, 

 pi. 10, fig?. 3 & 4. 



1863. Amnicola emarginata, Frfld., Verh. Zool.-bot. Ges. Wien. 

 XIII., p. 1030. 



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

 p. 85, fig. 169. 



