Note on a very fine example of Helicoceras stevonsoni preserving the outer chamber. Bulletin of the AMNH ; v. 14, article 16.

Whitfield, Robert Parr, 1828-1910.2005-10-062005-10-061901http://hdl.handle.net/2246/736p. 219, [2] leaves of plates : ill. ; 24 cm.75510 bytesapplication/pdfen-USQH1 .A4 vol.14, art.16, 1901Helicoceras stevonsoni.Ammonoidea -- Nebraska -- Chadron.Mollusks, Fossil -- Nebraska -- Chadron.Paleontology -- Cretaceous -- Nebraska -- Chadron.Paleontology -- Nebraska -- Chadron.Note on a very fine example of Helicoceras stevonsoni preserving the outer chamber. Bulletin of the AMNH ; v. 14, article 16.text