THE NAUTILUS. Ill 



known to occur within about 200 miles of the localities assigned 

 by Rafinesque for E. gihbosa (Ohio and Wabash), and in a 

 different drainage. Tryon thought ElUpstoma was Anculosn. 

 Other guesses (we did not call them identifications) made inde- 

 pendently by Dr. Bryant Walker and the writer did not agree, 

 and Dr. Dall declined to make a specific identification. It may 

 be that others, with keener discernment, may arrive at a result 

 satisfactory to themselves; but it seems to me unwise to base 

 nomenclature upon a diagnosis of such doubtful application. 



ylm6/oxis Rafinesque, Amer. Monthly Mag., Ill, p. 355, 1818. 

 The diagnosis of this genus agrees better with the group usually 

 known as Melantho or Campeloma than with any other of the 

 region, and no doubt it had the species subsolida Anth. or a 

 related form as a basis. Rafinesque mentioned, but did not 

 describe, A. eburnea and A. ventricosa. Mr. Binney, in Land 

 and Fresh-water Shells II, p. 45, figured Lyrnmda ventricosa and 

 Lymnea eburnea from Rafinesque' s MS. work Conchologia Ohio- 

 ensis, both being placed in the synonymy of Melantho decisa. 

 Binney mentions also, that L. eburnea was figured under the 

 names Ambloxis, Amblostoma, or Lymnidus major, or Lymnea 

 eburnea, by Rafinesque, in the MS. work mentioned. 



I select, therefore, the species eburnea Raf. as type of the 

 genera. Ambloxis (Raf., 1818) Amblostoma (Raf. MS. in Binney, 

 1865) and Lymnulus (Raf. MS. in Binney, 1865). Ambloxis 

 eburnea Raf. appears to be Paludina subsolida Anth., or possibly 

 some closely related form. As the species was in no way de- 

 fined by Rafinesque, remaining a nude name until Binney 

 figured it in 1865, it will become a synonym of Anthony's 

 species. 



Dr. Theodore Gill (Proc. A. N. S. Phila. 1864, p. 152) 

 recognized Ambloxis as identical with Campeloma, but said that 

 the ''insufficiency of the generic diagnosis as well as the want 

 of connection with any described species will prevent its adop- 

 tion." This was before Binney's publication.' Tryon (Amer. 



* Dr. Walker suggests that Gill h;id seen Binney's advance proofs, and did 

 not make an independent identification. Binney, however, only mentioned 

 Ambloxis incidentally. 



